censussm.gif (6303 bytes)

1990 Census of Population and Housing:

User Guide and Tutorial: Glossaries - Population Variables

APPENDIX B. Definitions of Subject Characteristics

CONTENTS

POPULATION CHARACTERISTICS B-2

Ability to Speak English (See Language Spoken at Home and Ability to Speak English)

Actual Hours Worked Last Week (See Employment Status)

Age B-2

American Indian Tribe (See Race)

Ancestry B-2

Carpooling (See Journey to Work)

Children Ever Born (See Fertility)

Citizenship B-4

Civilian Labor Force (See Employment Status)

Class of Worker (See Industry, Occupation, and Class of Worker)

Disability (See Mobility Limitation Status, see Self-Care Limitation Status, see

Work Disability Status)

Earnings in 1989 (See Income in 1989)

Educational Attainment B-4

Employment Status B-5

Families (See Household Type and Relationship)

Family Composition (See Household Type and Relationship)

Family Income in 1989 (See Income in 1989)

Family Size (See Household Type and Relationship)

Family Type (See Household Type and Relationship)

Farm Population (See Farm Residence under Housing Characteristics)

Fertility B-7

Foreign-Born Persons (See Place of Birth)

Foster Children (See Household Type and Relationship)

Group Quarters B-7

Hispanic Origin B-12

Household (See Household Type and Relationship)

Household Income in 1989 (See Income in 1989)

Household Language (See Language Spoken At Home and Ability

to Speak English)

Household Size (See Household Type and Relationship)

Household Type and Relationship B-13

Householder (See Household Type and Relationship)

Income Deficit (See Income in 1989)

Income in 1989 B-15

Income Type in 1989 (See Income in 1989)

Industry, Occupation, and Class of Worker B-19

Institutionalized Persons (See Group Quarters)

Journey to Work B-21

Labor Force Status (See Employment Status)

Language Spoken at Home and Ability to Speak English B-23

Linguistic Isolation (See Language Spoken at Home and Ability

to Speak English)

Marital Status B-25

Married Couples (See Marital Status)

Means of Transportation to Work (See Journey to Work)

Migration (See Residence in 1985)

Mobility Limitation Status B-26

Nativity (See Place of Birth)

Noninstitutionalized Group Quarters (See Group Quarters)

Occupation (See Industry, Occupation, and Class of Worker)

Own Children (See Household Type and Relationship)

Per Capita Income (See Income in 1989)

Period of Military Service (See Veteran Status)

Persons in Family (See Household Type and Relationship)

Persons in Households (See Household Type and Relationship)

Place of Birth B-26

Place of Work (See Journey to Work)

Poverty Status in 1989 B-27

Presence of Children (See Household Type and Relationship)

Private Vehicle Occupancy (See Journey to Work)

Race B-28

Reference Week B-31

Related Children (See Household Type and Relationship)

Residence in 1985 B-32

School Enrollment and Labor Force Status B-33

School Enrollment and Type of School B-33

Self-Care Limitation Status B-34

Sex B-34

Spanish Origin (See Hispanic Origin)

Stepfamily (See Household Type and Relationship)

Subfamily (See Household Type and Relationship)

Time Leaving Home to Go to Work (See Journey to Work)

Travel Time to Work (See Journey to Work)

Type of School (See School Enrollment and Type of School)

Usual Hours Worked Per Week Worked in 1989 (See Work Status in 1989)

Veteran Status B-34

Weeks Worked in 1989 (Work Status in 1989)

Work Disability Status B-35

Work Status in 1989 B-35

Worker (See Employment Status, see Industry, Occupation, and Class

of Worker, see Journey to Work, see Work Status in 1989)

Workers in Family in 1989 (See Work Status in 1989)

Year of Entry B-36

Years of Military Service (See Veteran Status)

HOUSING CHARACTERISTICS B-36

Acreage B-37

Age of Structure (See Year Structure Built)

Agricultural Sales B-38

Bedrooms B-38

Boarded-Up Status B-38

Business on Property B-38

Condominium Fee B-39

Condominium Status B-39

Congregate Housing (See Meals Included in Rent)

Contract Rent B-39

Crop Sales (See Agricultural Sales)

Duration of Vacancy B-40

Farm Residence B-40

Gross Rent B-40

Gross Rent as a Percentage of Household Income in 1989 B-41

Homeowner Vacancy Rate (See Vacancy Status)

House Heating Fuel B-41

Housing Units (See Living Quarters)

Insurance for Fire, Hazard, and Flood B-41

Kitchen Facilities B-41

Living Quarters B-36

Meals Included in Rent B-41

Mobile Home Costs B-42

Months Vacant (See Duration of Vacancy)

Mortgage Payment B-42

Mortgage Status B-42

Occupied Housing Units (See Living Quarters)

Owner-Occupied Housing Units (See Tenure)

Persons in Unit B-43

Persons Per Room B-43

Plumbing Facilities B-43

Poverty Status of Households in 1989 B-43

Real Estate Taxes B-43

Rental Vacancy Rate (See Vacancy Status)

Renter-Occupied Housing Units (See Tenure)

Rooms B-44

Second or Junior Mortgage Payment B-44

Selected Monthly Owner Costs B-44

Selected Monthly Owner Costs as a Percentage of Household

Income in 1989 B-45

Sewage Disposal B-45

Source of Water B-45

Telephone in Housing Unit B-45

Tenure B-46

Type of Structure (See Units in Structure)

Units in Structure B-46

Usual Home Elsewhere B-47

Utilities B-47

Vacancy Status B-47

Vacant Housing Units (See Living Quarters)

Value B-48

Vehicles Available B-48

Year Householder Moved Into Unit B-49

Year Structure Built B-49

DERIVED MEASURES B-49

Interpolation B-49

Mean B-49

Median B-49

Percentages, Rates, and Ratios B-50

Quartile B-50

POPULATION CHARACTERISTICS

AGE--The data on age were derived from answers to questionnaire

item 5, which was asked of all persons. The age classification is based

on the age of the person in complete years as of April 1, 1990. The age

response in question 5a was used normally to represent a person's age.

However, when the age response was unacceptable or unavailable, a

person's age was derived from an acceptable year-of-birth response in

question 5b.

Data on age are used to determine the applicability of other questions

for a person and to classify other characteristics in census

tabulations. Age data are needed to interpret most social and economic

characteristics used to plan and examine many programs and policies.

Therefore, age is tabulated by single years of age and by many

different groupings, such as 5-year age groups.

Some tabulations are shown by the age of the householder. These data

were derived from the age responses for each householder. (For more

information on householder, see the discussion under "Household Type

and Relationship.")

Median Age--This measure divides the age distribution into two equal parts:

one-half of the cases falling below the median value and one-half above

the value. Generally, median age is computed on the basis of more

detailed age intervals than are shown in some census publications;

thus, a median based on a less detailed distribution may differ

slightly from a corresponding median for the same population based on a

more detailed distribution. (For more information on medians, see the

discussion under "Derived Measures.")

Limitation of the Data--Counts in 1970 and 1980 for persons 100 years old

and over were substantially overstated. Improvements were made in the

questionnaire design, in the allocation procedures, and to the respondent

instruction guide to attempt to minimize this problem for the 1990 census.

Review of detailed 1990 census information indicated that respondents

tended to provide their age as of the date of completion of the

questionnaire, not their age as of April 1, 1990. In addition, there

may have been a tendency for respondents to round their age up if they

were close to having a birthday. It is likely that approximately 10

percent of persons in most age groups are actually 1 year younger. For

most single years of age, the misstatements are largely offsetting. The

problem is most pronounced at age 0 because persons lost to age 1 may not

have been fully offset by the inclusion of babies born after April 1, 1990,

and because there may have been more rounding up to age 1 to avoid

reporting age as 0 years. (Age in complete months was not collected for

infants under age 1.)

The reporting of age 1 year older than age on April 1, 1990, is likely

to have been greater in areas where the census data were collected

later in 1990. The magnitude of this problem was much less in the three

previous censuses where age was typically derived from respondent data

on year of birth and quarter of birth. (For more information on the

design of the age question, see the section below that discusses

"Comparability.")

Comparability--Age data have been collected in every census. For the first

time since 1950, the 1990 data are not available by quarter year of age.

This change was made so that coded information could be obtained for both

age and year of birth. In each census since 1940, the age of a person

was assigned when it was not reported. In censuses before 1940, with

the exception of 1880, persons of unknown age were shown as a separate

category. Since 1960, assignment of unknown age has been performed by a

general procedure described as "imputation." The specific

procedures for imputing age have been different in each census. (For

more information on imputation, see Appendix C, Accuracy of the Data.)

ANCESTRY--The data on ancestry were derived from answers to

questionnaire item 13, which was asked of a sample of persons. The

question was based on self-identification; the data on ancestry

represent self-classification by people according to the ancestry

group(s) with which they most closely identify. Ancestry refers to a

person's ethnic origin or descent, "roots," or heritage or the

place of birth of the person or the person's parents or ancestors

before their arrival in the United States. Some ethnic identities, such

as "Egyptian" or "Polish" can be traced to geographic areas

outside the United States, while other ethnicities such as

"Pennsylvania Dutch" or "Cajun" evolved in the United

States.

The intent of the ancestry question was not to measure the degree of

attachment the respondent had to a particular ethnicity. For example, a

response of "Irish" might reflect total involvement in an "Irish" community

or only a memory of ancestors several generations removed from the

individual.

The Census Bureau coded the responses through an automated review,

edit, and coding operation. The open-ended write-in ancestry item was coded

by subject-matter specialists into a numeric representation using a code

list containing over 1,000 categories. The 1990 code list reflects the

results of the Census Bureau's own research and consultations with many

ethnic experts. Many decisions were made to determine the classification of

responses. These decisions affected the grouping of the tabulated data. For

example, the "Assyrian" category includes both responses of "Assyrian"

and "Chaldean."

The ancestry question allowed respondents to report one or more

ancestry groups. While a large number of respondents listed a single

ancestry, the majority of answers included more than one ethnic entry.

Generally, only the first two responses reported were coded in 1990. If

a response was in terms of a dual ancestry, for example, Irish-English,

the person was assigned two codes, in this case one for Irish and

another for English.

However, in certain cases, multiple responses such as "French

Canadian," "Scotch-Irish," "Greek Cypriote," and "Black Dutch" were

assigned a single code reflecting their status as unique groups. If a

person reported one of these unique groups in addition to another group,

for example, "Scotch-Irish English," resulting in three terms, that person

received one code for the unique group ("Scotch-Irish") and another one for

the remaining group ("English"). If a person reported "English Irish

French," only English and Irish were coded. Certain combinations of

ancestries where the ancestry group is a part of another, such as "German-

Bavarian," the responses were coded as a single ancestry using the smaller

group ("Bavarian"). Also, responses such as "Polish-American" or

"Italian-American" were coded and tabulated as a single entry

("Polish" or "Italian").

The Census Bureau accepted "American" as a unique ethnicity if it

was given alone, with an ambiguous response, or with State names. If

the respondent listed any other ethnic identity such as "Italian

American," generally the "American" portion of the response

was not coded. However, distinct groups such as "American

Indian," "Mexican American," and "African American" were

coded and identified separately because they represented groups who

considered themselves different from those who reported as

"Indian," "Mexican," or "African," respectively.

In all tabulations, when respondents provided an unacceptable ethnic

identity (for example, an uncodeable or unintelligible response such as

"multi-national," "adopted," or "I have no idea"), the answer was included

in "Ancestry not reported."

The tabulations on ancestry are presented using two types of data

presentations--one used total persons as the base, and the other used

total responses as the base. The following are categories shown in the

two data presentations:

Presentation Based on Persons:

Single Ancestries Reported--Includes all persons who reported only one

ethnic group. Included in this category are persons with multiple-term

responses such as "Scotch-Irish" who are assigned a single code.

Multiple Ancestries Reported--Includes all persons who reported more than

one group and were assigned two ancestry codes.

Ancestry Unclassified--Includes all persons who provided a response that

could not be assigned an ancestry code because they provided nonsensical

entries or religious responses.

Presentations Based on Responses:

Total Ancestries Reported--Includes the total number of ancestries

reported and coded. If a person reported a multiple ancestry such as

"French Danish," that response was counted twice in the tabulations--once

in the "French" category and again in the "Danish" category. Thus, the

sum of the counts in this type of presentation is not the total

population but the total of all responses.

First Ancestry Reported--Includes the first response of all persons who

reported at least one codeable entry. For example, in this category, the

count for "Danish" would include all those who reported only Danish and

those who reported Danish first and then some other group.

Second Ancestry Reported--Includes the second response of all persons who

reported a multiple ancestry. Thus, the count for "Danish" in this

category includes all persons who reported Danish as the second response,

regardless of the first response provided.

The Census Bureau identified hundreds of ethnic groups in the 1990

census. However, it was impossible to show information for every group

in all census tabulations because of space constraints. Publications

such as the 1990 CP-2, Social and Economic Characteristics

and the 1990 CPH-3, Population and Housing Characteristics

for Census Tracts and Block Numbering Areas reports show a limited

number of groups based on the number reported and the advice received

from experts. A more complete distribution of groups is presented in

the 1990 Summary Tape File 4, supplementary reports, and a special

subject report on ancestry. In addition, groups identified specifically

in the questions on race and Hispanic origin (for example, Japanese,

Laotian, Mexican, Cuban, and Spaniard), in general, are not shown

separately in ancestry tabulations.

Limitation of the Data--Although some experts consider religious

affiliation a component of ethnic identity, the ancestry question was not

designed to collect any information concerning religion. The Bureau of the

Census is prohibited from collecting information on religion. Thus, if a

religion was given as an answer to the ancestry question, it was coded as

an "Other" response.

Comparability--A question on ancestry was first asked in

the 1980 census. Although there were no comparable data prior to the

1980 census, related information on ethnicity was collected through

questions on parental birthplace, own birthplace, and language which

were included in previous censuses. Unlike other census questions,

there was no imputation for nonresponse to the ancestry question.

In 1990, respondents were allowed to report more than one ancestry

group; however, only the first two ancestry groups identified were

coded. In 1980, the Census Bureau attempted to code a third ancestry

for selected triple-ancestry responses.

New categories such as "Arab" and "West Indian" were added to the 1990

question to meet important data needs. The "West Indian" category excluded

"Hispanic" groups such as "Puerto Rican" and "Cuban" that were identified

primarily through the question on Hispanic origin. In 1990, the ancestry

group, "American" is recognized and tabulated as a unique ethnicity. In

1980, "American" was tabulated but included under the category "Ancestry

not specified."

A major improvement in the 1990 census was the use of an automated

coding system for ancestry responses. The automated coding system used

in the 1990 census greatly reduced the potential for error associated

with a clerical review. Specialists with a thorough knowledge of the

subject matter reviewed, edited, coded, and resolved inconsistent or

incomplete responses.

CITIZENSHIP--The data on citizenship were derived from answers to

questionnaire item 9, which was asked of a sample of persons.

Citizen--Persons who indicated that they were native-born and foreign-born

persons who indicated that they have become naturalized. (For more

information on native and foreign born, see the discussion under "Place of

Birth.")

There are four categories of citizenship: (1) born in the United

States, (2) born in Puerto Rico, Guam, the Virgin Islands of the United

States, or the Commonwealth of the Northern Mariana Islands, (3) born

abroad of American parents, and (4) citizen by naturalization.

Naturalized Citizen--Foreign-born persons who had completed the

naturalization process at the time of the census and upon whom the rights

of citizenship had been conferred.

Not a Citizen--Foreign-born persons who were not citizens, including

persons who had begun but not completed the naturalization process at the

time of the census.

Limitation of the Data--Evaluation studies completed after previous

censuses indicated that some persons may have reported themselves as

citizens although they had not yet attained the status.

Comparability--Similar questions on citizenship were asked in the censuses

of 1820, 1830, 1870, 1890 through 1950, 1970, and 1980. The 1980 question

was asked of a sample of the foreign-born population. In 1990, both native

and foreign-born persons who received the long-form questionnaire were

asked to respond to the citizenship question.

EDUCATIONAL ATTAINMENT--Data on educational attainment were derived from

answers to questionnaire item 12, which was asked of a sample of persons.

Data are tabulated as attainment for persons 15 years old and over. Persons

are classified according to the highest level of school completed or the

highest degree received. The question included instructions to report the

level of the previous grade attended or the highest degree received for

persons currently enrolled in school. The question included response

categories which allowed persons to report completing the 12th grade

without receiving a high school diploma, and which instructed respondents

to report as "high school graduate(s)"--persons who received either a high

school diploma or the equivalent, for example, passed the Test of General

Educational Development (G.E.D.), and did not attend college. (On the

Military Census Report questionnaire, the lowest response category was

"Less than 9th grade.")

Instructions included in the 1990 respondent instruction guide, which

was mailed with the census questionnaire, further specified that

schooling completed in foreign or ungraded school systems should be

reported as the equivalent level of schooling in the regular American

system; that vocational certificates or diplomas from vocational,

trade, or business schools or colleges were not to be reported unless

they were college level degrees; and that honorary degrees were not to

be reported. The instructions gave "medicine, dentistry,

chiropractic, optometry, osteopathic medicine, pharmacy, podiatry,

veterinary medicine, law, and theology" as examples of professional

school degrees, and specifically excluded "barber school,

cosmetology, or other training for a specific trade" from the

professional school category. The order in which they were listed

suggested that doctorate degrees were "higher" than professional

school degrees, which were "higher" than master's degrees.

Persons who did not report educational attainment were assigned the

attainment of a person of the same age, race or Spanish origin, and sex

who resided in the same or a nearby area. Persons who filled more than

one circle were edited to the highest level or degree reported.

High School Graduate or Higher--Includes persons whose highest degree was a

high school diploma or its equivalent, persons who attended college or

professional school, and persons who received a college, university, or

professional degree. Persons who reported completing the 12th grade but not

receiving a diploma are not included.

Not Enrolled, Not High School Graduate--Includes persons of compulsory

school attendance age or above who were not enrolled in school and were not

high school graduates; these persons may be taken to be "high school

dropouts." There is no restriction on when they "dropped out" of school,

and they may have never attended high school.

In prior censuses, "Median school years completed" was used as

a summary measure of educational attainment. In 1990, the median can

only be calculated for groups of which less than half the members have

attended college. "Percent high school graduate or higher" and

"Percent bachelor's degree or higher" are summary measures which

can be calculated from the present data and offer quite readily

interpretable measures of differences between population subgroups. To

make comparisons over time, "Percent high school graduate or

higher" can be calculated and "Percent bachelor's degree or

higher" can be approximated with data from previous censuses.

Comparability--From 1840 to 1930, the census measured educational

attainment by means of a basic literacy question. In 1940, a single

question was asked on highest grade of school completed. In the censuses of

1950 through 1980, a two-part question asking highest grade of school

attended and whether that grade was finished was used to construct highest

grade or year of school completed. For persons who have not attended

college, the response categories in the 1990 educational attainment

question should produce data which are comparable to data on highest grade

completed from earlier censuses.

The response categories for persons who have attended college were

modified from earlier censuses because there was some ambiguity in

interpreting responses in terms of the number of years of college

completed. For instance, it was not clear whether "completed the

fourth year of college," "completed the senior year of

college," and "college graduate" were synonymous. Research

conducted shortly before the census suggests that these terms were more

distinct in 1990 than in earlier decades, and this change may have

threatened the ability to estimate the number of "college

graduates" from the number of persons reported as having completed

the fourth or a higher year of college. It was even more difficult to

make inferences about post-baccalaureate degrees and "Associate"

degrees from highest year of college completed. Thus, comparisons of

post-secondary educational attainment in this and earlier censuses

should be made with great caution.

In the 1960 and subsequent censuses, persons for whom educational

attainment was not reported were assigned the same attainment level as

a similar person whose residence was in the same or a nearby area. In

the 1940 and 1950 censuses, persons for whom educational attainment was

not reported were not allocated.

EMPLOYMENT STATUS--The data on employment status were derived from answers

to questionnaire items 21, 25, and 26, which were asked of a sample of

persons. The series of questions on employment status was asked of all

persons 15 years old and over and was designed to identify, in this

sequence: (1) persons who worked at any time during the reference week; (2)

persons who did not work during the reference week but who had jobs or

businesses from which they were temporarily absent (excluding layoff); (3)

persons on layoff; and (4) persons who did not work during the reference

week, but who were looking for work during the last four weeks and were

available for work during the reference week. (For more information, see

the discussion under "Reference Week.")

The employment status data shown in this and other 1990 census

tabulations relate to persons 16 years old and over. Some tabulations

showing employment status, however, include persons 15 years old. By

definition, these persons are classified as "Not in Labor

Force.". In the 1940, 1950, and 1960 censuses, employment status

data were presented for persons 14 years old and over. The change in

the universe was made in 1970 to agree with the official measurement of

the labor force as revised in January 1967 by the U.S. Department of

Labor. The 1970 census was the last to show employment data for persons

14 and 15 years old.

Employed--All civilians 16 years old and over who were either (1) "at

work"--those who did any work at all during the reference week as

paid employees, worked in their own business or profession, worked on

their own farm, or worked 15 hours or more as unpaid workers on a

family farm or in a family business; or (2) were "with a job but not

at work"--those who did not work during the reference week but had

jobs or businesses from which they were temporarily absent due to

illness, bad weather, industrial dispute, vacation, or other personal

reasons. Excluded from the employed are persons whose only activity

consisted of work around the house or unpaid volunteer work for

religious, charitable, and similar organizations; also excluded are

persons on active duty in the United States Armed Forces.

Unemployed--All civilians 16 years old and over are classified as

unemployed if they (1) were neither "at work" nor "with a job but not at

work" during the reference week, and (2) were looking for work

during the last 4 weeks, and (3) were available to accept a job. Also

included as unemployed are civilians who did not work at all during the

reference week and were waiting to be called back to a job from which

they had been laid off. Examples of job seeking activities are:

Registering at a public or private employment office

Meeting with prospective employers

Investigating possibilities for starting a professional

practice or opening a business

Placing or answering advertisements

Writing letters of application

Being on a union or professional register

Civilian Labor Force--Consists of persons classified as employed or

unemployed in accordance with the criteria described above.

Experienced Unemployed--These are unemployed persons who have worked at any

time in the past.

Experienced Civilian Labor Force--Consists of the employed and the

experienced unemployed.

Labor Force--All persons classified in the civilian labor force plus

members of the U.S. Armed Forces (persons on active duty with the United

States Army, Air Force, Navy, Marine Corps, or Coast Guard).

Not in Labor Force--All persons 16 years old and over who are not

classified as members of the labor force. This category consists mainly of

students, housewives, retired workers, seasonal workers enumerated in an

off season who were not looking for work, institutionalized persons, and

persons doing only incidental unpaid family work (less than 15 hours

during the reference week).

Worker--This term appears in connection with several subjects: journey-to-

work items, class of worker, weeks worked in 1989, and number of workers in

family in 1989. Its meaning varies and, therefore, should be determined

in each case by referring to the definition of the subject in which it

appears.

Actual Hours Worked Last Week--All persons who reported working during the

reference week were asked to report in questionnaire item 21b the number of

hours that they worked. The statistics on hours worked pertain to the

number of hours actually worked at all jobs, and do not necessarily reflect

the number of hours typically or usually worked or the scheduled number of

hours. The concept of "actual hours" differs from that of "usual

hours" described below. The number of persons who worked only a

small number of hours is probably understated since such persons

sometimes consider themselves as not working. Respondents were asked to

include overtime or extra hours worked, but to exclude lunch hours,

sick leave, and vacation leave.

Limitation of the Data--The census may understate the number of employed

persons because persons who have irregular, casual, or unstructured jobs

sometimes report themselves as not working. The number of employed persons

"at work" is probably overstated in the census (and conversely, the

number of employed "with a job, but not at work" is understated)

since some persons on vacation or sick leave erroneously reported

themselves as working. This problem has no effect on the total number

of employed persons. The reference week for the employment data is not

the same for all persons. Since persons can change their employment

status from one week to another, the lack of a uniform reference week

may mean that the employment data do not reflect the reality of the

employment situation of any given week. (For more information, see the

discussion under "Reference Week.")

Comparability--The questionnaire items and employment status concepts for

the 1990 census are essentially the same as those used in the 1980 and 1970

censuses. However, these concepts differ in many respects from those

associated with the 1950 and 1960 censuses.

Since employment data from the census are obtained from respondents in

households, they differ from statistics based on reports from

individual business establishments, farm enterprises, and certain

government programs. Persons employed at more than one job are counted

only once in the census and are classified according to the job at

which they worked the greatest number of hours during the reference

week. In statistics based on reports from business and farm

establishments, persons who work for more than one establishment may be

counted more than once. Moreover, some tabulations may exclude private

household workers, unpaid family workers, and self-employed persons,

but may include workers less than 16 years of age.

An additional difference in the data arises from the fact that persons

who had a job but were not at work are included with the employed in

the census statistics, whereas many of these persons are likely to be

excluded from employment figures based on establishment payroll

reports. Furthermore, the employment status data in census tabulations

include persons on the basis of place of residence regardless of where

they work, whereas establishment data report persons at their place of

work regardless of where they live. This latter consideration is

particularly significant when comparing data for workers who commute

between areas.

Census data on actual hours worked during the reference week may differ

from data from other sources. The census measures hours actually

worked, whereas some surveys measure hours paid for by employers.

Comparability of census actual hours worked data may also be affected

by the nature of the reference week (see "Reference Week").

For several reasons, the unemployment figures of the Census Bureau are

not comparable with published figures on unemployment compensation

claims. For example, figures on unemployment compensation claims

exclude persons who have exhausted their benefit rights, new workers

who have not earned rights to unemployment insurance, and persons

losing jobs not covered by unemployment insurance systems (including

some workers in agriculture, domestic services, and religious

organizations, and self-employed and unpaid family workers). In

addition, the qualifications for drawing unemployment compensation

differ from the definition of unemployment used by the Census Bureau.

Persons working only a few hours during the week and persons with a job

but not at work are sometimes eligible for unemployment compensation

but are classified as "Employed" in the census. Differences in

the geographical distribution of unemployment data arise because the

place where claims are filed may not necessarily be the same as the

place of residence of the unemployed worker.

The figures on employment status from the decennial census are

generally comparable with similar data collected in the Current

Population Survey. However, some difference may exist because of

variations in enumeration and processing techniques.

FERTILITY--The data on fertility (also referred to as "children ever born")

were derived from answers to questionnaire item 20, which was asked of a

sample of women 15 years old and over regardless of marital status.

Stillbirths, stepchildren, and adopted children were excluded from the

number of children ever born. Ever-married women were instructed to include

all children born to them before and during their most recent marriage,

children no longer living, and children away from home, as well as children

who were still living in the home. Never-married women were instructed to

include all children born to them.

Data are most frequently presented in terms of the aggregate number of

children ever born to women in the specified category and in terms of

the rate per 1,000 women. For purposes of calculating the aggregate,

the open-ended response category, "12 or more" is assigned a value of 13.

Limitation of the Data--Although the data are assumed to be less complete

for out-of-wedlock births than for births occurring within marriage,

comparisons of 1980 census data on the fertility of single women with other

census sources and administrative records indicate that no significant

differences were found between different data sources; that is, 1980 census

data on children ever born to single women were complete with no

significant understatements of childbearing.

Comparability--The wording of the question on children ever born was the

same in 1990 as in 1980. In 1970, however, the question on children ever

born was asked of all ever-married women but only of never-married women

who received self-administered questionnaires. Therefore, rates and numbers

of children ever born to single women in 1970 may be understated. Data

presented for children ever born to ever-married women are comparable

for the 1990 census and all previous censuses containing this question.

GROUP QUARTERS--All persons not living in households are classified by the

Census Bureau as living in group quarters. Two general categories of

persons in group quarters are recognized:

(1) institutionalized persons and

(2) other persons in group quarters (also referred to as

"noninstitutional group quarters").

Institutionalized Persons--Includes persons under formally authorized,

supervised care or custody in institutions at the time of enumeration. Such

persons are classified as "patients or inmates" of an institution

regardless of the availability of nursing or medical care, the length of

stay, or the number of persons in the institution. Generally,

institutionalized persons are restricted to the institutional buildings and

grounds (or must have passes or escorts to leave) and thus have limited

interaction with the surrounding community. Also, they are generally under

the care of trained staff who have responsibility for their safekeeping and

supervision.

Type of Institution--The type of institution was determined as part of

census enumeration activities. For institutions which specialize in only

one specific type of service, all patients or inmates were given the same

classification. For institutions which had multiple types of major

services (usually general hospitals and Veterans' Administration

hospitals), patients were classified according to selected types of wards.

For example, in psychiatric wards of hospitals, patients were classified in

"mental (psychiatric) hospitals"; in hospital wards for persons with

chronic diseases, patients were classified in "hospitals for the

chronically ill." Each patient or inmate was classified in only one type of

institution. Institutions include the following types:

Correctional Institutions--Includes prisons, Federal

detention centers, military stockades and jails, police lockups,

halfway houses, local jails, and other confinement facilities,

including work farms.

Prisons--Where persons convicted of crimes serve their

sentences. In some census products, the prisons are classified by two

types of control:

(1) "Federal" (operated by the Bureau of Prisons of the Department

of Justice) and (2) "State." Residents who are criminally insane were

classified on the basis of where they resided at the time of

enumeration: (1) in institutions (or hospital wards) operated by

departments of correction or similar agencies; or

(2) in institutions operated by departments of mental health or

similar agencies.

Federal Detention Centers--Operated by the Immigration

and Naturalization Service (INS) and the Bureau of Prisons. These

facilities include detention centers used by the Park Police; Bureau of

Indian Affairs Detention Centers; INS Centers, such as the INS Federal

Alien Detention Facility; INS Processing Centers; and INS Contract

Detention Centers used to detain aliens under exclusion or deportation

proceedings, as well as those aliens who have not been placed into

proceedings, such as custodial required departures; and INS Detention

Centers operated within local jails, and State and Federal prisons.

Military Stockades, Jails--Operated by military police

and used to hold persons awaiting trial or convicted of violating

military laws.

Local Jails and Other Confinement Facilities--Includes

facilities operated by counties and cities that primarily hold persons

beyond arraignment, usually for more than 48 hours. Also included in

this category are work farms used to hold persons awaiting trial or

serving time on relatively short sentences and jails run by private

businesses under contract for local governments (but not by

State governments).

Police Lockups--Temporary-holding facilities operated

by county and city police that hold persons for 48 hours or less only

if they have not been formally charged in court.

Halfway Houses--Operated for correctional purposes and include

probation and restitution centers, pre- release centers, and

community-residential centers.

Other Types of Correctional Institutions--Privately

operated correctional facilities and correctional facilities

specifically for alcohol/drug abuse.

Nursing Homes--Comprises a heterogeneous group of places. The majority

of patients are elderly, although persons who require nursing care

because of chronic physical conditions may be found in these homes

regardless of their age. Included in this category are skilled-nursing

facilities, intermediate-care facilities, long-term care rooms in wards

or buildings on the grounds of hospitals, or long-term care

rooms/nursing wings in congregate housing facilities.

Also included are nursing, convalescent, and rest homes, such as

soldiers', sailors', veterans', and fraternal or religious homes for

the aged, with or without nursing care. In some census products,

nursing homes are classified by type of ownership as "Federal,"

"State," "Private not-for-profit," and "Private for

profit."

Mental (Psychiatric) Hospitals--Includes hospitals or

wards for the criminally insane not operated by a prison, and

psychiatric wards of general hospitals and veterans' hospitals.

Patients receive supervised medical/nursing care from formally-trained

staff. In some census products, mental hospitals are classified by type

of ownership as "Federal," "State or local,"

"Private," and "Ownership not known."

Hospitals for Chronically Ill--Includes hospitals for

patients who require long-term care, including those in military

hospitals and wards for the chronically ill located on military bases;

or other hospitals or wards for the chronically ill, which include

tuberculosis hospitals or wards, wards in general and Veterans'

Administration hospitals for the chronically ill, neurological wards,

hospices, wards for patients with Hansen's Disease (leprosy) and other

incurable diseases, and other unspecified wards for the chronically

ill. Patients who had no usual home elsewhere were enumerated as part

of the institutional population in the wards of general and military

hospitals. Most hospital patients are at the hospital temporarily and

were enumerated at their usual place of residence. (For more

information, see "Wards in General and Military Hospitals for

Patients Who Have No Usual Home Elsewhere.")

Schools, Hospitals, or Wards for the Mentally Retarded--Includes those

institutions such as wards in hospitals for the mentally retarded, and

intermediate-care facilities for the mentally retarded that provide

supervised medical/nursing care from formally-trained staff. In some

census products, this category is classified by type of ownership as

"Federal," "State or local," "Private," and "Ownership not known."

Schools, Hospitals, or Wards for the Physically Handicapped--Includes

three types of institutions: institutions for the blind, those for the

deaf, and orthopedic wards and institutions for the physically

handicapped. Institutions for persons with speech problems are

classified with "institutions for the deaf." The category "orthopedic

wards and institutions for the physically handicapped" includes those

institutions providing relatively long-term care to accident victims,

and to persons with polio, cerebral palsy, and muscular dystrophy. In

some census products, this category is classified by type of ownership

as "Public," "Private," and "Ownership not known."

Hospitals, and Wards for Drug/Alcohol Abuse--Includes hospitals, and

hospital wards in psychiatric and general hospitals. These facilities

are equipped medically and designed for the diagnosis and treatment of

medical or psychiatric illnesses associated with alcohol or drug abuse.

Patients receive supervised medical care from formally-trained staff.

Wards in General and Military Hospitals for Patients Who

Have No Usual Home Elsewhere--Includes maternity, neonatal,

pediatric (including wards for boarder babies), military, and surgical

wards of hospitals, and wards for persons with infectious diseases.

Juvenile Institutions--Includes homes, schools, and other institutions

providing care for children (short- or long-term care). Juvenile

institutions include the following types:

Homes for Abused, Dependent, and Neglected Children--Includes

orphanages and other institutions which provide long-term care

(usually more than 30 days) for children. This category

is classified in some census products by type of ownership as

"Public" and "Private."

Residential Treatment Centers--Includes those institutions which

primarily serve children who, by clinical diagnosis, are moderately

or seriously disturbed emotionally. Also, these institutions provide

long-term treatment services, usually supervised or directed by a

psychiatrist.

Training Schools for Juvenile Delinquents--Includes residential

training schools or homes, and industrial schools, camps, or farms for

juvenile delinquents.

Public Training Schools for Juvenile Delinquents--Usually operated by

a State agency (for example, department of welfare, corrections, or a

youth authority). Some are operated by county and city governments.

These public training schools are specialized institutions serving

delinquent children, generally between the ages of 10 and 17 years

old, all of whom are committed by the courts.

Private Training Schools--Operated under private auspices. Some of the

children they serve are committed by the courts as delinquents. Others

are referred by parents or social agencies because of delinquent

behavior. One difference between private and public training schools

is that, by their administrative policy, private schools have control

over their selection and intake.

Detention Centers--Includes institutions providing short-term care (usually

30 days or less) primarily for delinquent children pending disposition of

their cases by a court. This category also covers diagnostic centers. In

practice, such institutions may be caring for both delinquent and neglected

children pending court disposition.

Other Persons in Group Quarters (also referred to as "noninstitutional

group quarters")--Includes all persons who live in group quarters other

than institutions. Persons who live in the following living quarters are

classified as "other persons in group quarters" when there are 10

or more unrelated persons living in the unit; otherwise, these living

quarters are classified as housing units.

Rooming Houses--Includes persons residing in rooming and boarding houses

and living in quarters with 10 or more unrelated persons.

Group Homes--Includes "community-based homes" that provide care and

supportive services. Such places include homes for the mentally ill,

mentally retarded, and physically handicapped; drug/alcohol halfway houses;

communes; and maternity homes for unwed mothers.

Homes for the Mentally Ill--Includes community-based homes that provide

care primarily for the mentally ill. In some data products, this category

is classified by type of ownership as "Federal," "State," "Private," and

"Ownership not known." Homes which combine treatment of the physically

handicapped with treatment of the mentally ill are counted as homes for the

mentally ill.

Homes for the Mentally Retarded--Includes community-based homes that

provide care primarily for the mentally retarded. Homes which combine

treatment of the physically handicapped with treatment of the mentally

retarded are counted as homes for the mentally retarded. This category is

classified by type of ownership in some census products, as "Federal,"

"State," "Private," or "Ownership not known."

Homes for the Physically Handicapped--Includes community-based homes for

the blind, for the deaf, and other community-based homes for the physically

handicapped. Persons with speech problems are classified with homes for the

deaf. In some census products, this category is classified by type of

ownership as "Public," "Private," or "Ownership not known."

Homes or Halfway Houses for Drug/Alcohol Abuse--Includes persons with no

usual home elsewhere in places that provide community-based care and

supportive services to persons suffering from a drug/alcohol addiction and

to recovering alcoholics and drug abusers. Places providing community-based

care for drug and alcohol abusers include group homes, detoxification

centers, quarterway houses (residential treatment facilities that work

closely with accredited hospitals), halfway houses, and recovery homes for

ambulatory, mentally competent recovering alcoholics and drug abusers

who may be re-entering the work force.

Maternity Homes for Unwed Mothers--Includes persons with no usual home

elsewhere in places that provide domestic care for unwed mothers and their

children. These homes may provide social services and post-natal care

within the facility, or may make arrangements for women to receive such

services in the community. Nursing services are usually available in the

facility.

Other Group Homes--Includes persons with no usual home elsewhere in

communes, foster care homes, and job corps centers with 10 or more

unrelated persons. These types of places provide communal living quarters,

generally for persons who have formed their own community in which they

have common interests and often share or own property jointly.

Religious Group Quarters--Includes, primarily, group quarters for nuns

teaching in parochial schools and for priests living in rectories. It also

includes other convents and monasteries, except those associated with a

general hospital or an institution.

College Quarters Off Campus--Includes privately-owned rooming and boarding

houses off campus, if the place is reserved exclusively for occupancy by

college students and if there are 10 or more unrelated persons. In census

products, persons in this category are classified as living in a college

dormitory.

Persons residing in certain other types of living arrangements are

classified as living in "noninstitutional group quarters" regardless of the

number of people sharing the unit. These include persons residing in the

following types of group quarters:

College Dormitories--Includes college students in

dormitories (provided the dormitory is restricted to students who do

not have their families living with them), fraternity and sorority

houses, and on-campus residential quarters used exclusively for those

in religious orders who are attending college. Students in

privately-owned rooming and boarding houses off campus are also

included, if the place is reserved exclusively for occupancy by

college-level students and if there are 10 or more unrelated persons.

Military Quarters--Includes military personnel living

in barracks and dormitories on base, in transient quarters on base for

temporary residents (both civilian and military), and on military

ships. However, patients in military hospitals receiving treatment for

chronic diseases or who had no usual home elsewhere, and persons being

held in military stockades were included as part of the institutional

population.

Agriculture Workers' Dormitories--Includes persons in

migratory farm workers' camps on farms, bunkhouses for ranch hands, and

other dormitories on farms, such as those on "tree farms."

Other Workers' Dormitories--Includes persons in logging

camps, construction workers' camps, firehouse dormitories, job-training

camps, energy enclaves (Alaska only), and nonfarm migratory workers'

camps (for example, workers in mineral and mining camps).

Emergency Shelters for Homeless Persons (with sleeping

facilities) and Visible in Street Locations--Includes persons

enumerated during the "Shelter-and-Street-Night" operation primarily on

March 20-21, 1990. Enumerators were instructed not to ask if a person

was "homeless." If a person was at one of the locations below on March

20-21, the person was counted as described below. (For more information

on the "Shelter-and-Street-Night" operation, see Appendix D, Collection

and Processing Procedures.) This category is divided into four

classifications:

Emergency Shelters for Homeless Persons (with sleeping

facilities)--Includes persons who stayed overnight on March 20,

1990, in permanent and temporary emergency housing, missions,

hotels/motels, and flophouses charging $12 or less (excluding taxes)

per night; Salvation Army shelters, hotels, and motels used

entirely for homeless persons regardless of the nightly rate

charged; rooms in hotels and motels used partially for the

homeless; and similar places known to have persons who have no usual

home elsewhere staying overnight. If not shown separately, shelters

and group homes that provide temporary sleeping facilities for

runaway, neglected, and homeless children are included in this

category in data products.

Shelters for Runaway, Neglected, and Homeless Children--Includes

shelters/group homes which provide temporary sleeping facilities for

juveniles.

Visible in Street Locations--Includes street blocks and open public

locations designated before March 20, 1990, by city and community officials

as places where the homeless congregate at night. All persons found at

predesignated street sites from 2 a.m. to 4 a.m. and leaving abandoned or

boarded-up buildings from 4 a.m. to 8 a.m. on March 21, 1990, were

enumerated during "street" enumeration, except persons in uniform such as

police and persons engaged in obvious money-making activities other than

begging or panhandling. Enumerators were instructed not to ask if a

person was "homeless."

This cannot be considered a complete count of all persons living on the

streets because those who were so well hidden that local people did not

know where to find them were likely to have been missed as were persons

moving about or in places not identified by local officials. It is also

possible that persons with homes could have been included in the count

of "visible in street locations" if they were present when the

enumerator did the enumeration of a particular block.

Predesignated street sites include street corners, parks, bridges,

persons emerging from abandoned and boarded-up buildings, noncommercial

campsites (tent cities), all-night movie theaters, all-night

restaurants, emergency hospital waiting rooms, train stations,

airports, bus depots, and subway stations.

Shelters for Abused Women (Shelters Against Domestic Violence or Family

Crisis Centers)--Includes community-based homes or shelters that provide

domiciliary care for women who have sought shelter from family violence and

who may have been physically abused. Most shelters also provide care for

children of abused women. These shelters may provide social services,

meals, psychiatric treatment, and counseling. In some census products,

"shelters for abused women" are included in the category "other

noninstitutional group quarters."

Dormitories for Nurses and Interns in General and Military

Hospitals--Includes group quarters for nurses and other staff

members. It excludes patients.

Crews of Maritime Vessels--Includes officers, crew members, and passengers

of maritime U.S. flag vessels. All ocean-going and Great Lakes ships are

included.

Staff Residents of Institutions--Includes staff residing in group quarters

on institutional grounds who provide formally-authorized, supervised care

or custody for the institutionalized population.

Other Nonhousehold Living Situations--Includes persons with no usual home

elsewhere enumerated during transient or "T-Night" enumeration at YMCA's,

YWCA's, youth hostels, commercial and government-run campgrounds,

campgrounds at racetracks, fairs, and carnivals, and similar transient

sites.

Living Quarters for Victims of Natural Disasters--Includes living quarters

for persons temporarily displaced by natural disasters.

Limitation of the Data--Two types of errors can occur in the classification

of "types of group quarters":

Misclassification of Group Quarters--During the 1990 Special Place

Prelist operation, the enumerator determined the type of group quarters

associated with each special place in their assignment. The enumerator

used the Alphabetical Group Quarters Code List and Index to the

Alphabetical Group Quarters Code List to assign a two-digit code

number followed by either an "I," for institutional, or an

"N," for noninstitutional to each group quarters. In 1990,

unacceptable group quarter codes were edited. (For more information on

editing of unacceptable data, see Appendix C, Accuracy of the Data.)

No Classification (unknowns)--The imputation rate for type of

institution was higher in 1980 (23.5 percent) than in 1970 (3.3

percent). Improvements were made to the 1990 Alphabetical Group

Quarters Code List; that is, the inclusion of more group quarters

categories and an "Index to the Alphabetical Group Quarters Code

List." (For more information on the allocation rates for Type of

Institution, see the allocation rates in 1990 CP-1, General

Population Characteristics.)

In previous censuses, allocation rates for demographic characteristics

(such as age, sex, race, and marital status) of the institutional

population were similar to those for the total population. The allocation

rates for sample characteristics such as school enrollment, highest grade

completed, income, and veteran status for the institutional and

noninstitutional group quarters population have been substantially higher

than the population in households at least as far back as the 1960 census.

The data, however, have historically presented a reasonable picture of the

institutional and noninstitutional group quarters population.

Shelter and Street Night (S-Night)--For the 1990 census "Shelter-and-

Street-Night" operation, persons well hidden, moving about, or in locations

enumerators did not visit were likely to be missed. The number of people

missed will never be known; thus, the 1990 census cannot be considered to

include a definitive count of America's total homeless population. It does,

however, give an idea of relative differences among areas of the country.

Other components were counted as part of regular census procedures.

The count of persons in shelters and visible on the street could have

been affected by many factors. How much the factors affected the count

can never be answered definitively, but some elements include:

How well enumerators were trained and how well they followed

procedures.

How well the list of shelter and street locations given to the

Census Bureau by the local government reflected the actual places that

homeless persons stay at night.

Cities were encouraged to open temporary shelters for census night,

and many did that and actively encouraged people to enter the shelters.

Thus, people who may have been on the street otherwise were in shelters

the night of March 20, so that the ratio of shelter-to-street

population could be different than usual.

The weather, which was unusually cold in some parts of the country,

could affect how likely people were to seek emergency shelter or to be

more hidden than usual if they stayed outdoors.

The media occasionally interfered with the ability to do the count.

How homeless people perceived the census and whether they wanted to

be counted or feared the census and hid from it.

The Census Bureau conducted two assessments of Shelter and Street

Night: (1) the quality of the lists of shelters used for the

Shelter-and-Street-Night operation, and (2) how well procedures were

followed by census- takers for the street count in parts of five cities

(Chicago, Los Angeles, New Orleans, New York, and Phoenix). Information

about these two assessments is available from the Chief, Center for

Survey Methods Research, Bureau of the Census, Washington, DC 20233.

Comparability--For the 1990 census, the definition of institutionalized

persons was revised so that the definition of "care" only includes persons

under organized medical or formally-authorized, supervised care or

custody. As a result of this change to the institutional definition,

maternity homes are classified as noninstitutional rather than

institutional group quarters as in previous censuses. The following

types of other group quarters are classified as institutional rather

than noninstitutional group quarters: "halfway houses (operated for

correctional purposes)" and "wards in general and military

hospitals for patients who have no usual home elsewhere," which

includes maternity, neonatal, pediatric, military, and surgical wards

of hospitals, other-purpose wards of hospitals, and wards for

infectious diseases. These changes should not significantly affect the

comparability of data with earlier censuses because of the relatively

small number of persons involved.

As in 1980, 10 or more unrelated persons living together were

classified as living in noninstitutional group quarters. In 1970, the

criteria was six or more unrelated persons.

Several changes also have occurred in the identification of specific

types of group quarters. For the first time, the 1990 census identifies

separately the following types of correctional institutions: persons in

halfway houses (operated for correctional purposes), military stockades

and jails, and police lockups. In 1990, tuberculosis hospitals or wards

are included with hospitals for the chronically ill; in 1980, they were

shown separately. For 1990, the noninstitutional group quarters

category, "Group homes" is further classified as: group homes for

drug/alcohol abuse; maternity homes (for unwed mothers), group homes

for the mentally ill, group homes for the mentally retarded, and group

homes for the physically handicapped. Persons living in communes,

foster-care homes, and job corps centers are classified with "Other

group homes" only if 10 or more unrelated persons share the unit;

otherwise, they are classified as housing units.

In 1990, workers' dormitories were classified as group quarters

regardless of the number of persons sharing the dorm. In 1980, 10 or

more unrelated persons had to share the dorm for it to be classified as

a group quarters. In 1960, data on persons in military barracks were

shown only for men. In subsequent censuses, they include both men and

women.

In 1990 census data products, the phrase "inmates of institutions" was

changed to "institutionalized persons." Also, persons living in

noninstitutional group quarters were referred to as "other persons in group

quarters," and the phrase "staff residents" was used for staff living in

institutions.

In 1990, there are additional institutional categories and noninstitutional

group quarters categories compared with the 1980 census. The institutional

categories added include "hospitals and wards for drug/alcohol abuse" and

"military hospitals for the chronically ill." The noninstitutional group

quarters categories added include emergency shelters for homeless persons;

shelters for runaway, neglected, and homeless children; shelters for abused

women; and visible-in-street locations. Each of these noninstitutional

group quarters categories was enumerated on March 20-21, 1990, during the

"Shelter-and-Street-Night" operation. (For more information on

the "Shelter-and-Street-Night" operation, see Appendix D, Collection and

Processing Procedures.)

HISPANIC ORIGIN--The data on Spanish/Hispanic origin were derived from

answers to questionnaire item 7, which was asked of all persons. Persons of

Hispanic origin are those who classified themselves in one of the

specific Hispanic origin categories listed on the questionnaire--"Mexican,"

"Puerto Rican," or "Cuban"--as well as those who indicated that they were

of "other Spanish/Hispanic" origin. Persons of "Other Spanish/Hispanic"

origin are those whose origins are from Spain, the Spanish-speaking

countries of Central or South America, or the Dominican Republic, or they

are persons of Hispanic origin identifying themselves generally as Spanish,

Spanish-American, Hispanic, Hispano, Latino, and so on. Write-in responses

to the "other Spanish/Hispanic" category were coded only for sample data.

Origin can be viewed as the ancestry, nationality group, lineage, or

country of birth of the person or the person's parents or ancestors

before their arrival in the United States. Persons of Hispanic origin

may be of any race.

Some tabulations are shown by the Hispanic origin of the householder.

In all cases where households, families, or occupied housing units are

classified by Hispanic origin, the Hispanic origin of the householder

is used. (See the discussion of householder under "Household Type

and Relationship.")

During direct interviews conducted by enumerators, if a person could

not provide a single origin response, he or she was asked to select,

based on self-identification, the group which best described his or her

origin or descent. If a person could not provide a single group, the

origin of the person's mother was used. If a single group could not be

provided for the person's mother, the first origin reported by the

person was used.

If any household member failed to respond to the Spanish/Hispanic

origin question, a response was assigned by the computer according to

the reported entries of other household members by using specific rules

of precedence of household relationship. In the processing of sample

questionnaires, responses to other questions on the questionnaire, such

as ancestry and place of birth, were used to assign an origin before

any reference was made to the origin reported by other household

members. If an origin was not entered for any household member, an

origin was assigned from another household according to the race of the

householder. This procedure is a variation of the general imputation

process described in Appendix C, Accuracy of the Data.

Comparability--There may be differences between the total Hispanic origin

population based on 100-percent tabulations and sample tabulations. Such

differences are the result of sampling variability, nonsampling error,

and more extensive edit procedures for the Spanish/Hispanic origin item

on the sample questionnaires. (For more information on sampling

variability and nonsampling error, see Appendix C, Accuracy of the

Data.)

The 1990 data on Hispanic origin are generally comparable with those

for the 1980 census. However, there are some differences in the format

of the Hispanic origin question between the two censuses. For 1990, the

word "descent" was deleted from the 1980 wording. In addition,

the term "Mexican-Amer." used in 1980 was shortened further to

"Mexican-Am." to reduce misreporting (of "American") in

this category detected in the 1980 census. Finally, the 1990 question

allowed those who reported as "other Spanish/Hispanic" to write

in their specific Hispanic origin group.

Misreporting in the "Mexican-Amer." category of the 1980 census

item on Spanish/Hispanic origin may affect the comparability of 1980

and 1990 census data for persons of Hispanic origin for certain areas

of the country. An evaluation of the 1980 census item on

Spanish/Hispanic origin indicated that there was misreporting in the

Mexican origin category by White and Black persons in certain areas.

The study results showed evidence that the misreporting occurred in the

South (excluding Texas), the Northeast (excluding the New York City

area), and a few States in the Midwest Region. Also, results based on

available data suggest that the impact of possible misreporting of

Mexican origin in the 1980 census was severe in those portions of the

above-mentioned regions where the Hispanic origin population was

generally sparse. However, national 1980 census data on the Mexican

origin population or total Hispanic origin population at the national

level was not seriously affected by the reporting problem. (For a more

detailed discussion of the evaluation of the 1980 census

Spanish/Hispanic origin item, see the 1980 census Supplementary

Reports.)

The 1990 and 1980 census data on the Hispanic population are not

directly comparable with 1970 Spanish origin data because of a number

of factors: (1) overall improvements in the 1980 and 1990 censuses, (2)

better coverage of the population, (3) improved question designs, and

(4) an effective public relations campaign by the Census Bureau with

the assistance of national and community ethnic groups.

Specific changes in question design between the 1980 and 1970 censuses

included the placement of the category "No, not Spanish/Hispanic"

as the first category in that question. (The corresponding category

appeared last in the 1970 question.) Also, the 1970 category

"Central or South American" was deleted because in 1970 some

respondents misinterpreted the category; furthermore, the designations

"Mexican-American" and "Chicano" were added to the Spanish/Hispanic origin

question in 1980. In the 1970 census, the question on Spanish origin was

asked of only a 5-percent sample of the population.

HOUSEHOLD TYPE AND RELATIONSHIP

Household--A household includes all the persons who occupy a housing unit.

A housing unit is a house, an apartment, a mobile home, a group of rooms,

or a single room that is occupied (or if vacant, is intended for occupancy)

as separate living quarters. Separate living quarters are those in which

the occupants live and eat separately from any other persons in the

building and which have direct access from the outside of the building or

through a common hall. The occupants may be a single family, one person

living alone, two or more families living together, or any other group of

related or unrelated persons who share living arrangements.

In 100-percent tabulations, the count of households or householders

always equals the count of occupied housing units. In sample tabulations,

the numbers may differ as a result of the weighting process.

Persons Per Household--A measure obtained by dividing the number of persons

in households by the number of households (or householders). In cases where

persons in households are cross-classified by race or Hispanic origin,

persons in the household are classified by the race or Hispanic origin of

the householder rather than the race or Hispanic origin of each individual.

Relationship to Householder

Householder--The data on relationship to householder were derived from

answers to questionnaire item 2, which was asked of all persons in housing

units. One person in each household is designated as the householder. In

most cases, this is the person, or one of the persons, in whose name the

home is owned, being bought, or rented and who is listed in column 1 of

the census questionnaire. If there is no such person in the household,

any adult household member 15 years old and over could be designated as

the householder.

Households are classified by type according to the sex of the

householder and the presence of relatives. Two types of householders

are distinguished: a family householder and a nonfamily householder. A

family householder is a householder living with one or more persons

related to him or her by birth, marriage, or adoption. The householder

and all persons in the household related to him or her are family

members. A nonfamily householder is a householder living alone or with

nonrelatives only.

Spouse--Includes a person married to and living with a householder. This

category includes persons in formal marriages, as well as persons in

common-law marriages.

The number of spouses is equal to the number of "married-couple families"

or "married-couple households" in 100-percent tabulations. The number of

spouses, however, is generally less than half of the number of "married

persons with spouse present" in sample tabulations, since more than one

married couple can live in a household, but only spouses of householders

are specifically identified as "spouse." For sample tabulations, the number

of "married persons with spouse present" includes married-couple

subfamilies and married-couple families.

Child--Includes a son or daughter by birth, a stepchild, or adopted child

of the householder, regardless of the child's age or marital status. The

category excludes sons-in-law, daughters-in-law, and foster children.

Natural-Born or Adopted Son/Daughter--A son or daughter of the householder

by birth, regardless of the age of the child. Also, this category includes

sons or daughters of the householder by legal adoption, regardless of the

age of the child. If the stepson/stepdaughter of the householder has been

legally adopted by the householder, the child is still classified as a

stepchild.

Stepson/Stepdaughter--A son or daughter of the householder through marriage

but not by birth, regardless of the age of the child. If the

stepson/stepdaughter of the householder has been legally adopted by the

householder, the child is still classified as a stepchild.

Own Child--A never-married child under 18 years who is a son or daughter by

birth, a stepchild, or an adopted child of the householder. In certain

tabulations, own children are further classified as living with two parents

or with one parent only. Own children of the householder living with two

parents are by definition found only in married-couple families.

In a subfamily, an "own child" is a never-married child under 18

years of age who is a son, daughter, stepchild, or an adopted child of

a mother in a mother-child subfamily, a father in a father-child subfamily,

or either spouse in a married-couple subfamily.

"Related children" in a family include own children and all other persons

under 18 years of age in the household, regardless of marital status, who

are related to the householder, except the spouse of the householder.

Foster children are not included since they are not related to the

householder.

Other Relatives--In tabulations, includes any household member related to

the householder by birth, marriage, or adoption, but not included

specifically in another relationship category. In certain detailed

tabulations, the following categories may be shown:

Grandchild--The grandson or granddaughter of the householder.

Brother/Sister--The brother or sister of the householder, including

stepbrothers, stepsisters, and brothers and sisters by adoption. Brothers-

in-law and sisters-in-law are included in the "Other relative" category on

the questionnaire.

Parent--The father or mother of the householder, including a stepparent or

adoptive parent. Fathers-in-law and mothers-in-law are included in the

"Other relative" category on the questionnaire.

Other Relatives--Anyone not listed in a reported category above who is

related to the householder by birth, marriage, or adoption (brother-in-law,

grandparent, nephew, aunt, mother-in-law, daughter-in-law, cousin, and so

forth).

Nonrelatives--Includes any household member, including foster children not

related to the householder by birth, marriage, or adoption. The following

categories may be presented in more detailed tabulations:

Roomer, Boarder, or Foster Child--Roomer, boarder, lodger, and foster

children or foster adults of the householder.

Housemate or Roommate--A person who is not related to the householder

and who shares living quarters primarily in order to share expenses.

Unmarried Partner--A person who is not related to the householder, who

shares living quarters, and who has a close personal relationship with

the householder.

Other Nonrelatives--A person who is not related by birth, marriage, or

adoption to the householder and who is not described by the categories

given above.

When relationship is not reported for an individual, it is imputed

according to the responses for age, sex, and marital status for that

person while maintaining consistency with responses for other

individuals in the household. (For more information on imputation, see

Appendix C, Accuracy of the Data.)

Unrelated Individual--An unrelated individual is: (1) a householder living

alone or with nonrelatives only, (2) a household member who is not related

to the householder, or (3) a person living in group quarters who is not an

inmate of an institution.

Family Type--A family consists of a householder and one or more other

persons living in the same household who are related to the householder by

birth, marriage, or adoption. All persons in a household who are

related to the householder are regarded as members of his or her

family. A household can contain only one family for purposes of census

tabulations. Not all households contain families since a household may

comprise a group of unrelated persons or one person living alone.

Families are classified by type as either a "married-couple family" or

"other family" according to the sex of the householder and the presence of

relatives. The data on family type are based on answers to questions on sex

and relationship which were asked on a 100-percent basis.

Married-Couple Family--A family in which the householder and his or her

spouse are enumerated as members of the same household.

Other Family:

Male Householder, No Wife Present--A family with a male

householder and no spouse of householder present.

Female Householder, No Husband Present--A family with a

female householder and no spouse of householder present.

Persons Per Family--A measure obtained by dividing the number of persons in

families by the total number of families (or family householders). In cases

where the measure, "persons in family" or "persons per family" are

cross-tabulated by race or Hispanic origin, the race or Hispanic origin

refers to the householder rather than the race or Hispanic origin of

each individual.

Subfamily--A subfamily is a married couple (husband and wife enumerated as

members of the same household) with or without never-married children

under 18 years old, or one parent with one or more never-married

children under 18 years old, living in a household and related to, but

not including, either the householder or the householder's spouse. The

number of subfamilies is not included in the count of families, since

subfamily members are counted as part of the householder's family.

Subfamilies are defined during processing of sample data. In selected

tabulations, subfamilies are further classified by type: married-couple

subfamilies, with or without own children; mother-child subfamilies;

and father-child subfamilies.

Lone parents include people maintaining either one-parent families or one-

parent subfamilies. Married couples include husbands and wives in both

married-couple families and married-couple subfamilies.

Unmarried-Partner Household--An unmarried-partner household is a household

other than a "married-couple household" that includes a householder and an

"unmarried partner." An "unmarried partner" can be of the same sex or of

the opposite sex of the householder. An "unmarried partner" in an

"unmarried- partner household" is an adult who is unrelated to the

householder, but shares living quarters and has a close personal

relationship with the householder.

Unmarried-Couple Household--An unmarried-couple household is composed of

two unrelated adults of the opposite sex (one of whom is the householder)

who share a housing unit with or without the presence of children under 15

years old.

Foster Children--Foster children are nonrelatives of the householder and

are included in the category, "Roomer, boarder, or foster child" on the

questionnaire. Foster children are identified as persons under 18 years

old and living in households that have no nonrelatives 18 years old and

over (who might be parents of the nonrelatives under 18 years old).

Stepfamily--A stepfamily is a "married-couple family" with at least one

stepchild of the householder present, where the householder is the

husband.

Comparability--The 1990 definition of a household is the same as that used

in 1980. The 1980 relationship category "Son/daughter" has been replaced

by two categories, "Natural-born or adopted son/daughter" and "Stepson/

stepdaughter." "Grandchild" has been added as a separate category. The 1980

nonrelative categories: "Roomer, boarder" and "Partner, roommate" have been

replaced by the categories "Roomer, boarder, or foster child," "Housemate,

roommate," and "Unmarried partner." The 1980 nonrelative category "Paid

employee" has been dropped.

INCOME IN 1989--The data on income in 1989 were derived from answers to

questionnaire items 32 and 33. Information on money income received in

the calendar year 1989 was requested from persons 15 years old and

over. "Total income" is the algebraic sum of the amounts reported

separately for wage or salary income; net nonfarm self-employment

income; net farm self-employment income; interest, dividend, or net

rental or royalty income; Social Security or railroad retirement

income; public assistance or welfare income; retirement or disability

income; and all other income. "Earnings" is defined as the

algebraic sum of wage or salary income and net income from farm and

nonfarm self-employment. "Earnings" represent the amount of

income received regularly before deductions for personal income taxes,

Social Security, bond purchases, union dues, medicare deductions, etc.

Receipts from the following sources are not included as income: money

received from the sale of property (unless the recipient was engaged in

the business of selling such property); the value of income "in

kind" from food stamps, public housing subsidies, medical care,

employer contributions for persons, etc.; withdrawal of bank deposits;

money borrowed; tax refunds; exchange of money between relatives living

in the same household; gifts and lump-sum inheritances, insurance

payments, and other types of lump-sum receipts.

Income Type in 1989--The eight types of income reported in the census are

defined as follows:

Wage or Salary Income--Includes total money earnings

received for work performed as an employee during the calendar year

1989. It includes wages, salary, Armed Forces pay, commissions, tips,

piece-rate payments, and cash bonuses earned before deductions were made

for taxes, bonds, pensions, union dues, etc.

Nonfarm Self-Employment Income--Includes net money income (gross

receipts minus expenses) from one's own business, professional

enterprise, or partnership. Gross receipts include the value of all

goods sold and services rendered. Expenses includes costs of goods

purchased, rent, heat, light, power, depreciation charges, wages and

salaries paid, business taxes (not personal income taxes), etc.

Farm Self-Employment Income--Includes net money income (gross receipts

minus operating expenses) from the operation of a farm by a person on

his or her own account, as an owner, renter, or sharecropper. Gross

receipts include the value of all products sold, government farm

programs, money received from the rental of farm equipment to others,

and incidental receipts from the sale of wood, sand, gravel, etc.

Operating expenses include cost of feed, fertilizer, seed, and other

farming supplies, cash wages paid to farmhands, depreciation charges,

cash rent, interest on farm mortgages, farm building repairs, farm taxes

(not State and Federal personal income taxes), etc. The value of fuel,

food, or other farm products used for family living is not included as

part of net income.

Interest, Dividend, or Net Rental Income--Includes interest on savings

or bonds, dividends from stockholdings or membership in associations,

net income from rental of property to others and receipts from boarders

or lodgers, net royalties, and periodic payments from an estate or trust

fund.

Social Security Income--Includes Social Security pensions and survivors

benefits and permanent disability insurance payments made by the Social

Security Administration prior to deductions for medical insurance, and

railroad retirement insurance checks from the U.S. Government. Medicare

reimbursements are not included.

Public Assistance Income--Includes: (1) supplementary security income

payments made by Federal or State welfare agencies to low income persons

who are aged (65 years old or over), blind, or disabled; (2) aid to

families with dependent children, and (3) general assistance. Separate

payments received for hospital or other medical care (vendor payments)

are excluded from this item.

Retirement or Disability Income--Includes: (1) retirement pensions and

survivor benefits from a former employer, labor union, or Federal,

State, county, or other governmental agency; (2) disability income from

sources such as worker's compensation; companies or unions; Federal,

State, or local government; and the U.S. military; (3) periodic receipts

from annuities and insurance; and (4) regular income from IRA and KEOGH

plans.

All Other Income--Includes unemployment compensation, Veterans

Administration (VA) payments, alimony and child support,

contributions received periodically from persons not living in the

household, military family allotments, net gambling winnings, and other

kinds of periodic income other than earnings.

Income of Households--Includes the income of the householder and all other

persons 15 years old and over in the household, whether related to the

householder or not. Because many households consist of only one person,

average household income is usually less than average family income.

Income of Families and Persons--In compiling statistics on family income,

the incomes of all members 15 years old and over in each family are summed

and treated as a single amount. However, for persons 15 years old and over,

the total amounts of their own incomes are used. Although the income

statistics covered the calendar year 1989, the characteristics of persons

and the composition of families refer to the time of enumeration (April

1990). Thus, the income of the family does not include amounts received by

persons who were members of the family during all or part of the

calendar year 1989 if these persons no longer resided with the family

at the time of enumeration. Yet, family income amounts reported by

related persons who did not reside with the family during 1989 but who

were members of the family at the time of enumeration are included.

However, the composition of most families was the same during 1989 as

in April 1990.

Median Income--The median divides the income distribution into two equal

parts, one having incomes above the median and the other having incomes

below the median. For households and families, the median income is based

on the distribution of the total number of units including those with no

income. The median for persons is based on persons with income. The

median income values for all households, families, and persons are

computed on the basis of more detailed income intervals than shown in

most tabulations. Median household or family income figures of $50,000

or less are calculated using linear interpolation. For persons,

corresponding median values of $40,000 or less are also computed using

linear interpolation. All other median income amounts are derived

through Pareto interpolation. (For more information on medians and

interpolation, see the discussion under "Derived Measures.")

Mean Income--This is the amount obtained by dividing the total income of a

particular statistical universe by the number of units in that universe.

Thus, mean household income is obtained by dividing total household income

by the total number of households. For the various types of income the

means are based on households having those types of income. "Per capita

income" is the mean income computed for every man, woman, and child in a

particular group. It is derived by dividing the total income of a

particular group by the total population in that group.

Care should be exercised in using and interpreting mean income values

for small subgroups of the population. Because the mean is influenced

strongly by extreme values in the distribution, it is especially

susceptible to the effects of sampling variability, misreporting, and

processing errors. The median, which is not affected by extreme values,

is, therefore, a better measure than the mean when the population base

is small. The mean, nevertheless, is shown in some data products for

most small subgroups because, when weighted according to the number of

cases, the means can be added to obtained summary measures for areas

and groups other than those shown in census tabulations.

Limitation of the Data--Since questionnaire entries for income frequently

are based on memory and not on records, many persons tended to forget minor

or irregular sources of income and, therefore, underreport their income.

Underreporting tends to be more pronounced for income sources that are

not derived from earnings, such as Social Security, public assistance,

or from interest, dividends, and net rental income.

There are errors of reporting due to the misunderstanding of the income

questions such as reporting gross rather than net dollar amounts for

the two questions on net self-employment income, which resulted in an

overstatement of these items. Another common error is the reporting of

identical dollar amounts in two of the eight type of income items where

a respondent with only one source of income assumed that the second

amount should be entered to represent total income. Such instances of

overreporting had an impact on the level of mean nonfarm or farm

self-employment income and mean total income published for the various

geographical subdivisions of the State.

Extensive computer editing procedures were instituted in the data

processing operation to reduce some of these reporting errors and to

improve the accuracy of the income data. These procedures corrected

various reporting deficiencies and improved the consistency of reported

income items associated with work experience and information on

occupation and class of worker. For example, if persons reported they

were self-employed on their own farm, not incorporated, but had

reported wage and salary earnings only, the latter amount was shifted

to net farm self-employment income. Also, if any respondent reported total

income only, the amount was generally assigned to one of the type of income

items according to responses to the work experience and class-of-worker

questions. Another type of problem involved nonreporting of income

data. Where income information was not reported, procedures were

devised to impute appropriate values with either no income or positive

or negative dollar amounts for the missing entries. (For more

information on imputation, see Appendix C, Accuracy of the Data.)

In income tabulations for households and families, the lowest income

group (e.g., less than $5,000) includes units that were classified as

having no 1989 income. Many of these were living on income "in

kind," savings, or gifts, were newly created families, or families

in which the sole breadwinner had recently died or left the household.

However, many of the households and families who reported no income

probably had some money income which was not recorded in the census.

The income data presented in the tabulations covers money income only.

The fact that many farm families receive an important part of their

income in the form of "free" housing and goods produced and

consumed on the farm rather than in money should be taken into

consideration in comparing the income of farm and nonfarm residents.

Nonmoney income such as business expense accounts, use of business

transportation and facilities, or partial compensation by business for

medical and educational expenses was also received by some nonfarm

residents. Many low income families also receive income "in kind"

from public welfare programs. In comparing income data for 1989 with

earlier years, it should be noted that an increase or decrease in money

income does not necessarily represent a comparable change in real

income, unless adjustments for changes in prices are made.

Comparability--The income data collected in the 1980 and 1970 censuses are

similar to the 1990 census data, but there are variations in the detail of

the questions. In 1980, income information for 1979 was collected from

persons in approximately 19 percent of all housing units and group

quarters. Each person was required to report:

Wage or salary income

Net nonfarm self-employment income

Net farm self-employment income

Interest, dividend, or net rental or royalty income Social Security

income

Public assistance income

Income from all other sources

Between the 1980 and 1990 censuses, there were minor differences in

the processing of the data. In both censuses, all persons with missing

values in one or more of the detailed type of income items

and total income were designated as allocated. Each

missing entry was imputed either as a "no" or as a dollar amount.

If total income was reported and one or more of the type of

income fields was not answered, then the entry in total income

generally was assigned to one of the income types according to the

socioeconomic characteristics of the income recipient. This person was

designated as unallocated.

In 1980 and 1990, all nonrespondents with income not reported (whether

heads of households or other persons) were assigned the reported income

of persons with similar characteristics. (For more information on

imputation, see Appendix C, "Accuracy of the Data.")

There was a difference in the method of computer derivation of

aggregate income from individual amounts between the two census

processing operations. In the 1980 census, income amounts less than

$100,000 were coded in tens of dollars, and amounts of $100,000 or more

were coded in thousands of dollars; $5 was added to each amount coded

in tens of dollars and $500 to each amount coded in thousands of

dollars. Entries of $999,000 or more were treated as $999,500 and

losses of $9,999 or more were treated as minus $9,999. In the 1990

census, income amounts less than $999,999 were keyed in dollars.

Amounts of $999,999 or more were treated as $999,999 and losses of

$9,999 or more were treated as minus $9,999 in all of the computer

derivations of aggregate income.

In 1970, information on income in 1969 was obtained from all members in

every fifth housing unit and small group quarters (less than 15

persons) and every fifth person in all other group quarters. Each

person was required to report:

Wage or salary income

Net nonfarm self-employment income

Net farm self-employment income

Social Security or Railroad Retirement

Public assistance or welfare payments

Income from all other sources

If a person reported a dollar amount in wage or salary, net nonfarm

self-employment income, or net farm self-employment income, the person was

considered as unallocated only if no further dollar amounts were imputed

for any additional missing entries.

In 1960, data on income were obtained from all members in every fourth

housing unit and from every fourth person 14 years old and over living

in group quarters. Each person was required to report wage or salary

income, net self-employment income, and income other than earnings

received in 1959. An assumption was made in the editing process that no

other type of income was received by a person who reported the receipt

of either wage and salary income or self-employment but who had failed

to report the receipt of other money income.

For several reasons, the income data shown in census tabulations are

not directly comparable with those that may be obtained from

statistical summaries of income tax returns. Income, as defined for

Federal tax purposes, differs somewhat from the Census Bureau concept.

Moreover, the coverage of income tax statistics is different because of

the exemptions of persons having small amounts of income and the

inclusion of net capital gains in tax returns. Furthermore, members of

some families file separate returns and others file joint returns;

consequently, the income reporting unit is not consistently either a

family or a person.

The earnings data shown in census tabulations are not directly

comparable with earnings records of the Social Security Administration.

The earnings record data for 1989 excluded the earnings of most

civilian government employees, some employees of nonprofit

organizations, workers covered by the Railroad Retirement Act, and

persons not covered by the program because of insufficient earnings.

Furthermore, earnings received from any one employer in excess of

$48,000 in 1989 are not covered by earnings records. Finally, because

census data are obtained from household questionnaires, they may differ

from Social Security Administration earnings record data, which are

based upon employers' reports and the Federal income tax returns of

self-employed persons.

The Bureau of Economic Analysis (BEA) of the Department of Commerce

publishes annual data on aggregate and per-capita personal income

received by the population for States, metropolitan areas, and selected

counties. Aggregate income estimates based on the income statistics

shown in census products usually would be less than those shown in the

BEA income series for several reasons. The Census Bureau data are

obtained directly from households, whereas the BEA income series is

estimated largely on the basis of data from administrative records of

business and governmental sources. Moreover, the definitions of income

are different. The BEA income series includes some items not included

in the income data shown in census publications, such as income "in

kind," income received by nonprofit institutions, the value of

services of banks and other financial intermediaries rendered to

persons without the assessment of specific charges, Medicare payments,

and the income of persons who died or emigrated prior to April 1, 1990.

On the other hand, the census income data include contributions for

support received from persons not residing in the same household and

employer contributions for social insurance.

INDUSTRY, OCCUPATION, AND CLASS OF WORKER--The data on industry,

occupation, and class of worker were derived from answers to questionnaire

items 28, 29, and 30 respectively. These questions were asked of a sample

of persons. Information on industry relates to the kind of business

conducted by a person's employing organization; occupation describes the

kind of work the person does on the job.

For employed persons, the data refer to the person's job during the

reference week. For those who worked at two or more jobs, the data

refer to the job at which the person worked the greatest number of

hours. For unemployed persons, the data refer to their last job. The

industry and occupation statistics are derived from the detailed

classification systems developed for the 1990 census as described

below. The Classified Index of Industries and Occupations

provided additional information on the industry and occupation

classification systems.

Respondents provided the data for the tabulations by writing on the

questionnaires descriptions of their industry and occupation. These

descriptions were keyed and passed through automated coding software

which assigned a portion of the written entries to categories in the

classification system. The automated system assigned codes to 59

percent of the industry entries and 38 percent of the occupation

entries.

Those cases not coded by the computer were referred to clerical staff

in the Census Bureau's Kansas City processing office for coding. The

clerical staff converted the written questionnaire descriptions to

codes by comparing these descriptions to entries in the

Alphabetical Index of Industries and Occupations. For the

industry code, these coders also referred to an Employer Name List

(formerly called Company Name List). This list, prepared from the

Standard Statistical Establishment List developed by the Census Bureau

for the economic censuses and surveys, contained the names of business

establishments and their Standard Industrial Classification (SIC) codes

converted to population census equivalents. This list facilitated

coding and maintained industrial classification comparability.

Industry--The industry classification system developed for the 1990 census

consists of 235 categories for employed persons, classified into 13

major industry groups. Since 1940, the industrial classification has

been based on the Standard Industrial Classification Manual (SIC). The

1990 census classification was developed from the 1987 SIC published by

the Office of Management and Budget Executive Office of the President.

The SIC was designed primarily to classify establishments by the type

of industrial activity in which they were engaged. However, census

data, which were collected from households, differ in detail and nature

from those obtained from establishment surveys. Therefore, the census

classification systems, while defined in SIC terms, cannot reflect the

full detail in all categories. There are several levels of industrial

classification found in census products. For example, the 1990 CP-2,

Social and Economic Characteristics report includes 41

unique industrial categories, while the 1990 Summary Tape File 4 (STF

4) presents 72 categories.

Occupation--The occupational classification system developed for the 1990

census consists of 500 specific occupational categories for employed

persons arranged into 6 summary and 13 major occupational groups. This

classification was developed to be consistent with the Standard

Occupational Classification (SOC) Manual: 1980, published by the Office

of Federal Statistical Policy and Standards, U.S. Department of

Commerce. Tabulations with occupation as the primary characteristic

present several levels of occupational detail. The most detailed

tabulations are shown in a special 1990 subject report and tape files

on occupation. These products contain all 500 occupational categories

plus industry or class of worker subgroupings of occupational

categories.

Some occupation groups are related closely to certain industries.

Operators of transportation equipment, farm operators and workers, and

private household workers account for major portions of their

respective industries of transportation, agriculture, and private

households. However, the industry categories include persons in other

occupations. For example, persons employed in agriculture include truck

drivers and bookkeepers; persons employed in the transportation

industry include mechanics, freight handlers, and payroll clerks; and

persons employed in the private household industry include occupations

such as chauffeur, gardener, and secretary.

Class of Worker--The data on class of worker were derived from answers to

questionnaire item 30. The information on class of worker refers to the

same job as a respondent's industry and occupation and categorizes

persons according to the type of ownership of the employing

organization. The class of worker categories are defined as follows:

Private Wage and Salary Workers--Includes persons who worked for wages,

salary, commission, tips, pay-in-kind, or piece rates for a private for

profit employer or a private not-for-profit, tax-exempt or charitable

organization. Self-employed persons whose business was incorporated are

included with private wage and salary workers because they are paid

employees of their own companies. Some tabulations present data

separately for these subcategories: "For profit," "Not for profit," and

"Own business incorporated."

Employees of foreign governments, the United Nations, or other formal

international organizations were classified as "Private-not-for-profit."

Government Workers--Includes persons who were employees of any local,

State, or Federal governmental unit, regardless of the activity of the

particular agency. For some tabulations, the data were presented

separately for the three levels of government.

Self-Employed Workers--Includes persons who worked for profit or fees in

their own unincorporated business, profession, or trade, or who operated

a farm.

Unpaid Family Workers--Includes persons who worked 15 hours or more

without pay in a business or on a farm operated by a relative.

Salaried/Self-Employed--In tabulations that categorize persons as either

salaried or self-employed, the salaried category includes private and

government wage and salary workers; self-employed includes self-employed

persons and unpaid family workers.

The industry category, "Public administration," is limited to regular

government functions such as legislative, judicial, administrative, and

regulatory activities of governments. Other government organizations

such as schools, hospitals, liquor stores, and bus lines are classified

by industry according to the activity in which they are engaged. On the

other hand, the class of worker government categories include all

government workers.

Occasionally respondents supplied industry, occupation, or class of

worker descriptions which were not sufficiently specific for precise

classification or did not report on these items at all. Some of these

cases were corrected through the field editing process and during the

coding and tabulation operations. In the coding operation, certain

types of incomplete entries were corrected using the Alphabetical

Index of Industries and Occupations. For example, it was possible

in certain situations to assign an industry code based on the

occupation reported.

Following the coding operations, there was a computer edit and an

allocation process. The edit first determined whether a respondent was

in the universe which required an industry and occupation code. The

codes for the three items (industry, occupation, and class of worker)

were checked to ensure they were valid and were edited for their

relation to each other. Invalid and inconsistent codes were either

blanked or changed to a consistent code.

If one or more of the three codes were blank after the edit, a code was

assigned from a "similar" person based on other items such as

age, sex, education, farm or nonfarm residence, and weeks worked. If

all the labor force and income data also were blank, all these economic

items were assigned from one other person who provided all the

necessary data.

Comparability--Comparability of industry and occupation data was affected

by a number of factors, primarily the systems used to classify the

questionnaire responses. For both the industry and occupation

classification systems, the basic structures were generally the same from

1940 to 1970, but changes in the individual categories limited

comparability of the data from one census to another. These changes were

needed to recognize the "birth" of new industries and occupations, the

"death" of others, and the growth and decline in existing industries and

occupations, as well as, the desire of analysts and other users for

more detail in the presentation of the data. Probably the greatest

cause of incomparability is the movement of a segment of a category to

a different category in the next census. Changes in the nature of jobs

and respondent terminology, and refinement of category composition made

these movements necessary.

In the 1990 census, the industry classification had minor revisions to

reflect recent changes to the SIC. The 1990 occupational classification

system is essentially the same as that for the 1980 census. However,

the conversion of the census classification to the SOC in 1980 meant

that the 1990 classification system was less comparable to the

classifications used prior to the 1980 census.

Other factors that affected data comparability included the universe to

which the data referred (in 1970, the age cutoff for labor force was

changed from 14 years to 16 years); how the industry and occupation

questions were worded on the questionnaire (for example, important

changes were made in 1970); improvements in the coding procedures (the

Employer Name List technique was introduced in 1960); and how the

"not reported" cases are handled. Prior to 1970, they were placed

in the residual categories, "Industry not reported" and

"Occupation not reported." In 1970, an allocation process was

introduced that assigned these cases to major groups. In 1990, as in

1980, the "Not reported" cases were assigned to individual

categories. Therefore, the 1980 and 1990 data for individual categories

included some numbers of persons who were tabulated in a "Not

reported" category in previous censuses.

The following publications contain information on the various factors

affecting comparability and are particularly useful for understanding

differences in the occupation and industry information from earlier

censuses: U.S. Bureau of the Census, Changes Between the 1950 and

1960 Occupation and Industry Classifications With Detailed Adjustments

of 1950 Data to the 1960 Classifications, Technical Paper No. 18,

1968; U.S. Bureau of the Census, 1970 Occupation and Industry

Classification Systems in Terms of their 1960 Occupation and Industry

Elements, Technical Paper No. 26, 1972; and U.S. Bureau of the

Census, The Relationship Between the 1970 and 1980 Industry and

Occupation Classification Systems, Technical Paper No. 59, 1988.

For citations for earlier census years, see the 1980 Census of

Population report, PC80-1-D, Detailed Population

Characteristics.

The 1990 census introduced an additional class of worker category for

"private not-for-profit" employers. This category is a subset of

the 1980 category "employee of private employer" so there is no

comparable data before 1990. Also in 1990, employees of foreign

governments, the United Nations, etc., are classified as "private

not-for-profit," rather than Federal Government as in 1970 and 1980. While

in theory, there was a change in comparability, in practice, the small

number of U.S. residents working for foreign governments made this

change negligible.

Comparability between the statistics on industry and occupation from

the 1990 census and statistics from other sources is affected by many

of the factors described in the section on "Employment Status."

These factors are primarily geographic differences between residence

and place of work, different dates of reference, and differences in

counts because of dual job holding. Industry data from population

censuses cover all industries and all kinds of workers, whereas, data

from establishments often excluded private household workers,

government workers, and the self-employed. Also, the replies from

household respondents may have differed in detail and nature from those

obtained from establishments.

Occupation data from the census and data from government licensing

agencies, professional associations, trade unions, etc., may not be as

comparable as expected. Organizational listings often include persons

not in the labor force or persons devoting all or most of their time to

another occupation; or the same person may be included in two or more

different listings. In addition, relatively few organizations, except

for those requiring licensing, attained complete coverage of membership

in a particular occupational field.

JOURNEY TO WORK

Place of Work--The data on place of work were derived from answers to

questionnaire item 22, which was asked of persons who indicated in question

21 that they worked at some time during the reference week. (For more

information, see discussion under "Reference Week.")

Data were tabulated for workers 16 years and over; that is, members of

the Armed Forces and civilians who were at work during the reference

week. Data on place of work refer to the geographic location at which

workers carried out their occupational activities during the reference

week. The exact address (number and street) of the place of work was

asked, as well as the place (city, town, or post office); whether or

not the place of work was inside or outside the limits of that city or

town; and the county, State, and ZIP Code. If the person's employer

operated in more than one location, the exact address of the location

or branch where the respondent worked was requested. When the number

and street name were unknown, a description of the location, such as

the building name or nearest street or intersection, was to be entered.

Persons who worked at more than one location during the reference week

were asked to report the one at which they worked the greatest number

of hours. Persons who regularly worked in several locations each day

during the reference week were requested to give the address at which

they began work each day. For cases in which daily work did not begin

at a central place each day, the person was asked to provide as much

information as possible to describe the area in which he or she worked

most during the reference week.

In some tabulations, place-of-work locations may be defined as "in

area of residence" and "outside area of residence." The area

of residence may vary from table to table or even within a table, and

refers to the particular area or areas shown. For example, in a table

that provides data for counties, "in area of residence" refers to

persons who worked in the same county in which they lived, while

"outside area of residence" refers to persons whose workplace was

located in a county different from the one in which they lived.

Similarly, in a table that provides data for several types of areas,

such as the State and its individual metropolitan areas (MA's),

counties, and places, the place-of-work data will be variable and is

determined by the geographic level (State, MA, county, or place) shown in

each section of the tabulation.

In tabulations that present data for States, workplaces for the

residents of the State may include, in addition to the State itself,

each contiguous State. The category, "in noncontiguous State or

abroad," includes persons who worked in a State that did not border

their State of residence as well as persons who worked outside the

United States.

In tabulations that present data for an MSA/PMSA, place-of-work

locations are specified to show the main destinations of workers living

in the MSA/PMSA. (For more information on metropolitan areas (MA's),

see Appendix A, Area Classifications.) All place-of-work locations are

identified with respect to the boundaries of the MSA/PMSA as "inside

MSA/PMSA" or "outside MSA/PMSA." Locations within the MSA/PMSA

are further divided into each central city, and each county or county

balance. Selected large incorporated places also may be specified as

places of work.

Within New England MSA/PMSA's, the places of work presented generally

are cities and towns. Locations outside the MSA/PMSA are specified if

they are important commuting destinations for residents of the

MSA/PMSA, and may include adjoining MSA/PMSA's and their central

cities, their component counties, large incorporated places, or

counties, cities, or other geographic areas outside any MA. In

tabulations for MSA/PMSA's in New England; Honolulu, Hawaii; and

certain other MA's, some place-of-work locations are identified as "areas"

(e.g., Area 1, Area 5, Area 12, etc.). Such areas consist of groups of

towns, cities, census designated places (Honolulu MSA only), or counties

that have been identified as unique place-of-work destinations. When an

adjoining MSA/PMSA or MSA/PMSA remainder is specified as a place-of-work

location, its components are not defined. However, the components are

presented in the 1990 CP-1, General Population Characteristics

for Metropolitan Areas and the 1990 CH-1, General Housing

Characteristics for Metropolitan Areas reports. In tabulations

that present data for census tracts outside MA's, place-of-work

locations are defined as "in county of residence" and "outside

county of residence."

In areas where the workplace address was coded to the block level,

persons were tabulated as working inside or outside a specific place

based on the location of that address, regardless of the response to

question 22c concerning city/town limits. In areas where it was

impossible to code the workplace address to the block level, persons

were tabulated as working in a place if a place name was reported in

question 22b and the response to question 22c was either "Yes" or

the item was left blank. In selected areas, census designated places

(CDP's) may appear in the tabulations as places of work. The accuracy

of place-of-work data for CDP's may be affected by the extent to which

their census names were familiar to respondents, and by coding problems

caused by similarities between the CDP name and the names of other

geographic jurisdictions in the same vicinity.

Place-of-work data are given for selected minor civil divisions

(generally, cities, towns, and townships) in the nine Northeastern

States, based on the responses to the place-of-work question. Many

towns and townships are regarded locally as equivalent to a place and

therefore, were reported as the place of work. When a respondent

reported a locality or incorporated place that formed a part of a

township or town, the coding and tabulating procedure was designed to

include the response in the total for the township or town. The

accuracy of the place-of-work data for minor civil divisions is

greatest for the New England States. However, the data for some New

England towns, for towns in New York, and for townships in New Jersey

and Pennsylvania may be affected by coding problems that resulted from

the unfamiliarity of the respondent with the minor civil division in

which the workplace was located or when a township and a city or

borough of the same or similar name are located close together.

Place-of-work data may show a few workers who made unlikely daily work

trips (e.g., workers who lived in New York and worked in California).

This result is attributable to persons who worked during the reference

week at a location that was different from their usual place of work,

such as persons away from home on business.

Comparability--The wording of the question on place of work was

substantially the same in the 1990 census as it was in 1980.

However, data on place of work from the 1990 census are based on the

full census sample, while data from the 1980 census were based on only

about one-half of the full sample.

For the 1980 census, nonresponse or incomplete responses to the

place-of-work question were not allocated, resulting in the use of

"not reported" categories in the 1980 publications. However, for

the 1990 census, when place of work was not reported or the response

was incomplete, a work location was allocated to the person based on

their means of transportation to work, travel time to work, industry,

and location of residence and workplace of others. The 1990

publications, therefore, do not contain a "not reported" category

for the place-of-work data.

Comparisons between 1980 and 1990 census data on the gross number of

workers in particular commuting flows, or the total number of persons

working in an area, should be made with extreme caution. Any apparent

increase in the magnitude of the gross numbers may be due solely to the

fact that for 1990 the "not reported" cases have been distributed

among specific place-of-work destinations, instead of tallied in a

separate category as in 1980.

Limitation of the Data--The data on place of work relate to a reference

week; that is, the calendar week preceding the date on which the

respondents completed their questionnaires or were

interviewed by enumerators. This week is not the same for all

respondents because the enumeration was not completed in 1 week.

However, for the majority of persons, the reference week for the 1990

census is the last week in March 1990. The lack of a uniform reference

week means that the place-of-work data reported in the census will not

exactly match the distribution of workplace locations observed or

measured during an actual workweek.

The place-of-work data are estimates of persons 16 years old and over

who were both employed and at work during the reference week (including

persons in the Armed Forces). Persons who did not work during the

reference week but had jobs or businesses from which they were

temporarily absent due to illness, bad weather, industrial dispute,

vacation, or other personal reasons are not included in the

place-of-work data. Therefore, the data on place of work understate the

total number of jobs or total employment in a geographic area during

the reference week. It also should be noted that persons who had

irregular, casual, or unstructured jobs during the reference week may

have erroneously reported themselves as not working.

The address where the individual worked most often during the reference

week was recorded on the census questionnaire. If a worker held two

jobs, only data about the primary job (the one worked the greatest

number of hours during the preceding week) was requested. Persons who

regularly worked in several locations during the reference week were

requested to give the address at which they began work each day. For

cases in which daily work was not begun at a central place each day,

the person was asked to provide as much information as possible to

describe the area in which he or she worked most during the reference

week.

Means of Transportation to Work--The data on means of transportation to

work were derived from answers to questionnaire item 23a, which was asked

of persons who indicated in question 21 that they worked at some time

during the reference week. (For more information, see discussion under

"Reference Week.") Means of transportation to work refers to the

principal mode of travel or type of conveyance that the person usually

used to get from home to work during the reference week.

Persons who used different means of transportation on different days of

the week were asked to specify the one they used most often, that is,

the greatest number of days. Persons who used more than one means of

transportation to get to work each day were asked to report the one

used for the longest distance during the work trip. The category,

"Car, truck, or van," includes workers using a car (including

company cars but excluding taxicabs), a truck of one-ton capacity or

less, or a van. The category, "Public transportation," includes

workers who used a bus or trolley bus, streetcar or trolley car, subway

or elevated, railroad, ferryboat, or taxicab even if each mode is not

shown separately in the tabulation. The category, "Other means,"

includes workers who used a mode of travel which is not identified

separately within the data distribution. The category, "Other

means," may vary from table to table, depending on the amount of

detail shown in a particular distribution.

The means of transportation data for some areas may show workers using

modes of public transportation that are not available in those areas

(e.g., subway or elevated riders in an MA where there actually is no

subway or elevated service). This result is largely due to persons who

worked during the reference week at a location that was different from

their usual place of work (such as persons away from home on business

in an area where subway service was available) and persons who used

more than one means of transportation each day but whose principal

means was unavailable where they lived (for example, residents of

nonmetropolitan areas who drove to the fringe of an MA and took the

commuter railroad most of the distance to work).

Private Vehicle Occupancy--The data on private vehicle occupancy were

derived from answers to questionnaire item 23b. This question was asked of

persons who indicated in question 21 that they worked at some time during

the reference week and who reported in question 23a that their means of

transportation to work was "Car, truck, or van." (For more

information, see discussion under "Reference Week.")

Private vehicle occupancy refers to the number of persons who usually

rode to work in the vehicle during the reference week. The category,

"Drove alone," includes persons who usually drove alone to work

as well as persons who were driven to work by someone who then drove

back home or to a nonwork destination. The category, "Carpooled,"

includes workers who reported that two or more persons usually rode to

work in the vehicle during the reference week.

Persons Per Car, Truck, or Van--This is obtained by dividing the number of

persons who reported using a car, truck, or van to get to work by the

number of such vehicles that they used. The number of vehicles used is

derived by counting each person who drove alone as one vehicle, each person

who reported being in a two-person carpool as one-half vehicle, each person

who reported being in a three-person carpool as one-third vehicle, and so

on, and then summing all the vehicles.

Time Leaving Home to Go to Work--The data on time leaving home to go to

work were derived from answers to questionnaire item 24a. This question was

asked of persons who indicated in question 21 that they worked at some time

during the reference week and who reported in question 23a that they worked

outside their home. The departure time refers to the time of day that

the person usually left home to go to work during the reference week.

(For more information, see discussion under "Reference Week.")

Travel Time to Work--The data on travel time to work were derived from

answers to questionnaire item 24b. This question was asked of persons who

indicated in question 21 that they worked at some time during the

reference week and who reported in question 23a that they worked

outside their home. Travel time to work refers to the total number of

minutes that it usually took the person to get from home to work during

the reference week. The elapsed time includes time spent waiting for

public transportation, picking up passengers in carpools, and time

spent in other activities related to getting to work. (For more

information, see discussion under "Reference Week.")

LANGUAGE SPOKEN AT HOME AND ABILITY TO SPEAK ENGLISH

Language Spoken at Home--Data on language spoken at home were derived from

the answers to questionnaire items 15a and 15b, which were asked of a

sample of persons born before April 1, 1985. Instructions mailed with the

1990 census questionnaire stated that a respondent should mark "Yes"

in question 15a if the person sometimes or always spoke a language

other than English at home and should not mark "Yes" if a

language was spoken only at school or if speaking was limited to a few

expressions or slang. For question 15b, respondents were instructed to

print the name of the non-English language spoken at home. If the

person spoke more than one language other than English, the person was

to report the language spoken more often or the language learned first.

The cover of the census questionnaire included information in Spanish

which provided a telephone number for respondents to call to request a

census questionnaire and instructions in Spanish. Instruction guides

were also available in 32 other languages to assist enumerators who

encountered households or respondents who spoke no English.

Questions 15a and 15b referred to languages spoken at home in an effort

to measure the current use of languages other than English. Persons who

knew languages other than English but did not use them at home or who

only used them elsewhere were excluded. Persons who reported speaking a

language other than English at home may also speak English; however,

the questions did not permit determination of the main or dominant

language of persons who spoke both English and another language. (For

more information, see discussion below on "Ability to Speak

English.")

For persons who indicated that they spoke a language other than English

at home in question 15a, but failed to specify the name of the language

in question 15b, the language was assigned based on the language of

other speakers in the household; on the language of a person of the

same Spanish origin or detailed race group living in the same or a

nearby area; or on a person of the same ancestry or place of birth. In

all cases where a person was assigned a non-English language, it was

assumed that the language was spoken at home. Persons for whom the name

of a language other than English was entered in question 15b, and for

whom question 15a was blank were assumed to speak that language at

home.

The write-in responses listed in question 15b (specific language

spoken) were transcribed onto computer files and coded into more than

380 detailed language categories using an automated coding system. The

automated procedure compared write-in responses reported by respondents

with entries in a computer dictionary, which initially contained

approximately 2,000 language names. The dictionary was updated with a

large number of new names, variations in spelling, and a small number

of residual categories. Each write-in response was given a numeric code

that was associated with one of the detailed categories in the

dictionary. If the respondent listed more than one non-English

language, only the first was coded.

The write-in responses represented the names people used for languages

they speak. They may not match the names or categories used by

linguists. The sets of categories used are sometimes geographic and

sometimes linguistic. Figure 1 provides an illustration of the content

of the classification schemes used to present language data. For more

information, write to the Chief, Population Division, U.S. Bureau of

the Census, Washington, DC 20233.

Household Language--In households where one or more persons (age 5 years

old or over) speak a language other than English, the household language

assigned to all household members is the non-English language spoken by the

first person with a non-English language in the following order:

householder, spouse, parent, sibling,

child, grandchild, other relative, stepchild, unmarried partner,

housemate or roommate, roomer, boarder, or foster child, or other

nonrelative. Thus, persons who speak only English may have a

non-English household language assigned to them in tabulations of

persons by household language.

---------------------------------------------------------------------------

Figure 1. Four- and Twenty-Five-Group Classifications of 1990 Census

Languages Spoken at Home with Illustrative Examples

Four-Group Twenty-Five-Group Examples

Classification Classification

---------------------------------------------------------------------------

Spanish Spanish Spanish, Ladino

Other Indo- French French, Cajun,

European French Creole

Italian

Portuguese

German

Yiddish

Other West Afrikaans, Dutch,

Germanic Pennsylvania Dutch

Scandanavian Danish, Norwegian,

Swedish

Polish

Russian

South Slavic Serbocroatian,

Bulgarian, Macedonian,

Slovene

Other Slavic Czech, Slovak,

Ukranian

Greek

Indic Hindi, Bengali,

Gujarathi, Punjabi,

Romany, Sinhalese

Other Indo- Armenian, Gaelic,

European, not Lithuanian, Persian

elsewhere classified

Languages of Chinese

Asia and the Japanese

Pacific Mon-Khmer Cambodian

Tagalog

Korean

Vietnamese

Other languages Chamorro, Dravidian

(part) Languages, Hawaiian,

Ilocano, Thai, Turkish

All other lan- Arabic

guages Hungarian

Native North

American languages

Other languages Amharic, Syriac,

(part) Finnish, Hebrew,

Languages of

Central and South

America, Other

Languages of Africa

---------------------------------------------------------------------------

Ability to Speak English--Persons 5 years old and over who reported that

they spoke a language other than English in question 15a were also asked in

question 15c to indicate their ability to speak English based on one of the

following categories: "Very well," "Well," "Not well," or "Not at all."

The data on ability to speak English represent the person's own

perception about his or her own ability or, because census

questionnaires are usually completed by one household member, the

responses may represent the perception of another household member. The

instruction guides and questionnaires that were mailed to households

did not include any information on how to interpret the response

categories in question 15c.

Persons who reported that they spoke a language other than English

at home but whose ability to speak English was not reported, were

assigned the English-language ability of a randomly selected person of

the same age, Spanish origin, nativity and year of entry, and language

group.

Linguistic Isolation-- A household in which no person age 14 years or over

speaks only English and no person age 14 years or over who speaks a

language other than English speaks English "Very well" is classified as

"linguistically isolated." All the members of a linguistically isolated

household are tabulated as linguistically isolated, including members under

age 14 years who may speak only English.

Limitation of the Data--Persons who speak a language other than English at

home may have first learned that language at school. However, these persons

would be expected to indicate that they spoke English "Very well." Persons

who speak a language other than English, but do not do so at home, should

have been reported as not speaking a language other than English at home.

The extreme detail in which language names were coded may give a false

impression of the linguistic precision of these data. The names used by

speakers of a language to identify it may reflect ethnic, geographic,

or political affiliations and do not necessarily respect linguistic

distinctions. The categories shown in the tabulations were chosen on a

number of criteria, such as information about the number of speakers of

each language that might be expected in a sample of the United States

population.

Comparability--Information on language has been collected in every census

since 1890. The comparability of data among censuses is limited by changes

in question wording, by the subpopulations to whom the question was

addressed, and by the detail that was published.

The same question on language was asked in the 1980 and 1990 censuses.

This question on the current language spoken at home replaced the

questions asked in prior censuses on mother tongue; that is, the

language other than English spoken in the person's home when he or she

was a child; one's first language; or the language spoken before

immigrating to the United States. The censuses of 1910-1940, 1960 and

1970 included questions on mother tongue. A change in coding procedure

from 1980 to 1990 should have improved accuracy of coding and may

affect the number of persons reported in some of the 380 plus

categories. It should not greatly affect the 4-group or 25- group

lists. In 1980, coding clerks supplied numeric codes for the written

entries on each questionnaire using a 2,000 name reference list. In

1990 written entries were transcribed to a computer file and matched to

a computer dictionary which began with the 2,000 name list, but

expanded as unmatched names were referred to headquarters specialists

for resolution.

The question on ability to speak English was asked for the first time

in 1980. In tabulations from 1980, the categories "Very well" and

"Well" were combined. Data from other surveys suggested a major

difference between the category "Very well" and the remaining

categories. In tabulations showing ability to speak English, persons

who reported that they spoke English "Very well" are presented

separately from persons who reported their ability to speak English as

less than "Very well."

MARITAL STATUS--The data on marital status were derived from answers to

questionnaire item 6, which was asked of all persons. The marital

status classification refers to the status at the time of enumeration.

Data on marital status are tabulated only for persons 15 years old and

over.

All persons were asked whether they were "now married," "widowed,"

"divorced," "separated," or "never married." Couples who live together

(unmarried persons, persons in common-law marriages) were allowed to report

the marital status they considered the most appropriate.

Never Married--Includes all persons who have never been married, including

persons whose only marriage(s) was annulled.

Ever Married--Includes persons married at the time of enumeration

(including those separated), widowed, or divorced.

Now Married, Except Separated--Includes persons whose current marriage has

not ended through widowhood, divorce, or separation (regardless of previous

marital history). The category may also include couples who live together

or persons in common-law marriages if they consider this category the most

appropriate. In certain tabulations, currently married persons are

further classified as "spouse present" or "spouse absent."

Separated--Includes persons legally separated or otherwise absent from

their spouse because of marital discord. Included are persons who have been

deserted or who have parted because they no longer want to live

together but who have not obtained a divorce.

Widowed--Includes widows and widowers who have not remarried.

Divorced--Includes persons who are legally divorced and who have not

remarried.

In selected sample tabulations, data for married and separated persons are

reorganized and combined with information on the presence of the spouse in

the same household.

Now Married--All persons whose current marriage has not ended by widowhood

or divorce. This category includes persons defined above as "separated."

Spouse Present--Married persons whose wife or husband was enumerated as a

member of the same household, including those whose spouse may have been

temporarily absent for such reasons as travel or hospitalization.

Spouse Absent--Married persons whose wife or husband was not enumerated as

a member of the same household. This category also includes all married

persons living in group quarters.

Separated--Defined above.

Spouse Absent, Other--Married persons whose wife or husband was not

enumerated as a member of the same household, excluding separated. Included

is any person whose spouse was employed and living away from home or in an

institution or absent in the Armed Forces.

Differences between the number of currently married males and the

number of currently married females occur because of reporting

differences and because some husbands and wives have their usual

residence in different areas. In sample tabulations, these differences

can also occur because different weights are applied to the

individual's data. Any differences between the number of "now

married, spouse present" males and females are due solely to sample

weighting. By definition, the numbers would be the same.

When marital status was not reported, it was imputed according to the

relationship to the householder and sex and age of the person. (For

more information on imputation, see Appendix C, Accuracy of the Data.)

Comparability--The 1990 marital status definitions are the same as those

used in 1980 with the exception of the term "never married" which replaces

the term "single" in tabulations. A general marital status question

has been asked in every census since 1880.

MOBILITY LIMITATION STATUS--The data on mobility limitation status were

derived from answers to questionnaire item 19a, which was asked of a sample

of persons 15 years old and over. Persons were identified as having a

mobility limitation if they had a health condition that had lasted for 6 or

more months and which made it difficult to go outside the home alone.

Examples of outside activities on the questionnaire included shopping and

visiting the doctor's office.

The term "health condition" referred to both physical and mental

conditions. A temporary health problem, such as a broken bone that was

expected to heal normally, was not considered a health condition.

Comparability--This was the first time that a question on mobility

limitation was included in the census.

PLACE OF BIRTH--The data on place of birth were derived from answers to

questionnaire item 8, which was asked on a sample basis. The

place-of-birth question asked respondents to report the U.S. State,

commonwealth or territory, or the foreign country where they were born.

Persons born outside the United States were asked to report their place

of birth according to current international boundaries. Since numerous

changes in boundaries of foreign countries have occurred in the last

century, some persons may have reported their place of birth in terms

of boundaries that existed at the time of their birth or emigration, or

in accordance with their own national preference.

Persons not reporting place of birth were assigned the birthplace of

another family member or were allocated the response of another person

with similar characteristics. Persons allocated as foreign born were

not assigned a specific country of birth but were classified as

"Born abroad, country not specified."

Nativity--Information on place of birth and citizenship were used to

classify the population into two major categories: native and foreign born.

When information on place of birth was not reported, nativity was assigned

on the basis of answers to citizenship, if reported, and other

characteristics.

Native--Includes persons born in the United States, Puerto Rico, or an

outlying area of the United States. The small number of persons who were

born in a foreign country but have at least one American parent also are

included in this category.

The native population is classified in the following groups: persons

born in the State in which they resided at the time of the census;

persons born in a different State, by region; persons born in Puerto

Rico or an outlying area of the U.S.; and persons born abroad with at

least one American parent.

Foreign Born--Includes persons not classified as "Native." Prior to the

1970 census, persons not reporting place of birth were generally classified

as native.

The foreign-born population is shown by selected area, country, or

region of birth: the places of birth shown in data products were

selected based on the number of respondents who reported that area or

country of birth.

Comparability--Data on the State of birth of the native population have

been collected in each census beginning with that of 1850. Similar data

were shown in tabulations for the 1980 census and other recent censuses.

Nonresponse was allocated in a similar manner in 1980; however, prior to

1980, nonresponse to the place of birth question was not allocated. Prior

to the 1970 census, persons not reporting place of birth were generally

classified as native.

The questionnaire instruction to report mother's State of residence

instead of the person's actual State of birth (if born in a hospital

in a different State) was dropped in 1990. Evaluation studies of 1970

and 1980 census data demonstrated that this instruction was generally

either ignored or misunderstood. Since the hospital and the mother's

residence is in the same State for most births, this change may have a

slight effect on State of birth data for States with large metropolitan

areas that straddle State lines.

POVERTY STATUS IN 1989--The data on poverty status were derived from

answers to the same questions as the income data, questionnaire items 32

and 33. (For more information, see the discussion under "Income in 1989.")

Poverty statistics presented in census publications were based on a

definition originated by the Social Security Administration in 1964 and

subsequently modified by Federal interagency committees in 1969 and

1980 and prescribed by the Office of Management and Budget in Directive

14 as the standard to be used by Federal agencies for statistical

purposes.

At the core of this definition was the 1961 economy food plan, the

least costly of four nutritionally adequate food plans designed by the

Department of Agriculture. It was determined from the Agriculture

Department's 1955 survey of food consumption that families of three or

more persons spend approximately one-third of their income on food;

hence, the poverty level for these families was set at three times the

cost of the economy food plan. For smaller families and persons living

alone, the cost of the economy food plan was multiplied by factors that

were slightly higher to compensate for the relatively larger fixed

expenses for these smaller households.

The income cutoffs used by the Census Bureau to determine the poverty

status of families and unrelated individuals included a set of 48

thresholds arranged in a two-dimensional matrix consisting of family

size (from one person to nine or more persons) cross-classified by

presence and number of family members under 18 years old (from no

children present to eight or more children present). Unrelated

individuals and two-person families were further differentiated by age

of the householder (under 65 years old and 65 years old and over).

The total income of each family or unrelated individual in the sample

was tested against the appropriate poverty threshold to determine the

poverty status of that family or unrelated individual. If the total

income was less than the corresponding cutoff, the family or unrelated

individual was classified as "below the poverty level." The

number of persons below the poverty level was the sum of the number of

persons in families with incomes below the poverty level and the number

of unrelated individuals with incomes below the poverty level.

The poverty thresholds are revised annually to allow for changes in the

cost of living as reflected in the Consumer Price Index. The average

poverty threshold for a family of four persons was $12,674 in 1989.

(For more information, see table A below.) Poverty thresholds were

applied on a national basis and were not adjusted for regional, State

or local variations in the cost of living. For a detailed discussion of

the poverty definition, see U.S. Bureau of the Census, Current

Population Reports, Series P-60, No. 171, Poverty in the United

States: 1988 and 1989.

---------------------------------------------------------------------------

Table A. Poverty Thresholds in 1989 by Size of Family and Number

of Related Children Under 18 Years

Weight Related children under 18 years

Size of average Eight

Family Unit thresholds None One Two Three Four Five Six Seven or more

---------------------------------------------------------------------------

One person

(unrelated

individual) $6,310

Under 65 yrs. 6 451 $6,451

65 yrs. &

over 5,947 5,947

Two persons 8,076

Householder

under 65 yrs. 8,343 8,303 $8,547

Householder

65 yrs. & over 7,501 7,495 8,515

Three persons 9,885 9,699 9,981 $9,990

Four persons 12,674 12,790 12,999 12,575 $12,619

Five persons 14,990 15,424 15,648 15,169 14,798 $14,572

Six persons 16,921 17,740 17,811 17,444 17,092 16,569 $16,259

Seven persons 19,162 20,412 20,540 20,101 19,794 19,224 18,558 $17,828

Eight persons 21,328 22,830 23,031 22,617 22,253 21,738 21,084 20,403 $20,230

Nine or

more persons 25,480 27,463 27,596 27,229 26,921 26,415 25,719 25,089 24,933 $23,973

---------------------------------------------------------------------------

Persons for Whom Poverty Status is Determined-- Poverty status was

determined for all persons except institutionalized persons, persons in

military group quarters and in college dormitories, and unrelated

individuals under 15 years old. These groups also were excluded from the

denominator when calculating poverty rates.

Specified Poverty Levels--Since the poverty levels currently in use by the

Federal Government do not meet all the needs of data users, some of the

data are presented for alternate levels. These specified poverty levels are

obtained by multiplying the income cutoffs at the poverty level by the

appropriate factor. For example, the average income cutoff at 125 percent

of poverty level was $15,843 ($12,674 x 1.25) in 1989 for a family of four

persons.

Weighted Average Thresholds at the Poverty Level--The average thresholds

shown in the first column of table A are weighted by the presence and

number of children. For example, the weighted average threshold for a given

family size is obtained by multiplying the threshold for each presence and

number of children category within the given family size by the number of

families in that category. These products are then aggregated across the

entire range of presence and number of children categories, and the

aggregate is divided by the total number of families in the group to yield

the weighted average threshold at the poverty level for that family size.

Since the basic thresholds used to determine the poverty status of

families and unrelated individuals are applied to all families and

unrelated individuals, the weighted average poverty thresholds are

derived using all families and unrelated individuals rather than just

those classified as being below the poverty level. To obtain the

weighted poverty thresholds for families and unrelated individuals

below alternate poverty levels, the weighted thresholds shown in table

A may be multiplied directly by the appropriate factor. The weighted

average thresholds presented in the table are based on the March 1990

Current Population Survey. However, these thresholds would not differ

significantly from those based on the 1990 census.

Income Deficit--Represents the difference between the total income of

families and unrelated individuals below the poverty level and their

respective poverty thresholds. In computing the income deficit, families

reporting a net income loss are assigned zero dollars and for such cases

the deficit is equal to the poverty threshold.

This measure provided an estimate of the amount which would be required

to raise the incomes of all poor families and unrelated individuals to

their respective poverty thresholds. The income deficit is thus a

measure of the degree of impoverishment of a family or unrelated

individual. However, caution must be used in comparing the average

deficits of families with different characteristics. Apparent

differences in average income deficits may, to some extent, be a

function of differences in family size.

Mean Income Deficit--Represents the amount obtained by dividing the total

income deficit of a group below the poverty level by the number of families

(or unrelated individuals) in that group.

Comparability--The poverty definition used in the 1990 and 1980 censuses

differed slightly from the one used in the 1970 census. Three technical

modifications were made to the definition used in the 1970 census as

described below:

1. The separate thresholds for families with a female householder with

no husband present and all other families were eliminated. For the 1980

and 1990 censuses, the weighted average of the poverty thresholds for

these two types of families was applied to all types of families,

regardless of the sex of the householder.

2. Farm families and farm unrelated individuals no longer had a set of

poverty thresholds that were lower than the thresholds applied to

nonfarm families and unrelated individuals. The farm thresholds were 85

percent of the corresponding levels for nonfarm families in the 1970

census. The same thresholds were applied to all families and unrelated

individuals regardless of residence in 1980 and 1990.

3. The thresholds by size of family were extended from seven or more

persons in 1970 to nine or more persons in 1980 and 1990.

These changes resulted in a minimal increase in the number of poor

at the national level. For a complete discussion of these modifications

and their impact, see the Current Population Reports, Series P-60, No.

133.

The population covered in the poverty statistics derived from the 1980

and 1990 censuses was essentially the same as in the 1970 census. The

only difference was that in 1980 and 1990, unrelated individuals under

15 years old were excluded from the poverty universe, while in 1970,

only those under 14 years old were excluded. The poverty data from the

1960 census excluded all persons in group quarters and included all

unrelated individuals regardless of age. It was unlikely that these

differences in population coverage would have had significant impact

when comparing the poverty data for persons since the 1960 censuses.

Current Population Survey--Because of differences in the questionnaires and

data collection procedures, estimates of the number of persons below the

poverty level by various characteristics from the 1990 census may differ

from those reported in the March 1990 Current Population Survey.

RACE--The data on race were derived from answers to questionnaire item 4,

which was asked of all persons. The concept of race as used by the

Census Bureau reflects self-identification; it does not denote any

clear-cut scientific definition of biological stock. The data for race

represent self-classification by people according to the race with

which they most closely identify. Furthermore, it is recognized that

the categories of the race item include both racial and national origin

or socio-cultural groups.

During direct interviews conducted by enumerators, if a person could

not provide a single response to the race question, he or she was asked

to select, based on self-identification, the group which best described

his or her racial identity. If a person could not provide a single race

response, the race of the mother was used. If a single race response

could not be provided for the person's mother, the first race reported

by the person was used. In all cases where occupied housing units,

households, or families are classified by race, the race of the

householder was used.

The racial classification used by the Census Bureau generally adheres

to the guidelines in Federal Statistical Directive No. 15, issued by

the Office of Management and Budget, which provides standards on ethnic

and racial categories for statistical reporting to be used by all

Federal agencies. The racial categories used in the 1990 census data

products are provided below.

White--Includes persons who indicated their race as "White" or reported

entries such as Canadian, German, Italian, Lebanese, Near Easterner,

Arab, or Polish.

Black--Includes persons who indicated their race as "Black or Negro" or

reported entries such as African American, Afro-American, Black Puerto

Rican, Jamaican, Nigerian, West Indian, or Haitian.

American Indian, Eskimo, or Aleut--Includes persons who classified

themselves as such in one of the specific race categories identified below.

American Indian--Includes persons who indicated their race as "American

Indian," entered the name of an Indian tribe, or reported such entries as

Canadian Indian, French-American Indian, or Spanish-American Indian.

American Indian Tribe--Persons who identified themselves as American Indian

were asked to report their enrolled or principal tribe. Therefore, tribal

data in tabulations reflect the written tribal entries reported on the

questionnaires. Some of the entries (for example, Iroquois, Sioux, Colorado

River, and Flathead) represent nations or reservations.

The information on tribe is based on self-identification and therefore

does not reflect any designation of Federally- or State-recognized

tribe. Information on American Indian tribes is presented in summary

tape files and special data products. The information is derived from

the American Indian Detailed Tribal Classification List for the 1990

census. The classification list represents all tribes, bands, and clans

that had a specified number of American Indians reported on the census

questionnaire.

Eskimo--Includes persons who indicated their race as "Eskimo" or reported

entries such as Arctic Slope, Inupiat, and Yupik.

Aleut--Includes persons who indicated their race as "Aleut" or reported

entries such as Alutiiq, Egegik, and Pribilovian.

Asian or Pacific Islander--Includes persons who reported in one of the

Asian or Pacific Islander groups listed on the questionnaire or who

provided write-in responses such as Thai, Nepali, or Tongan. A more

detailed listing of the groups comprising the Asian or Pacific Islander

population is presented in figure 2 below. In some data products,

information is presented separately for the Asian population and the

Pacific Islander population.

Asian--Includes "Chinese," "Filipino," "Japanese," "Asian Indian,"

"Korean," "Vietnamese," and "Other Asian." In some tables, "Other Asian"

may not be shown separately, but is included in the total Asian population.

Chinese--Includes persons who indicated their race as "Chinese" or who

identified themselves as Cantonese, Tibetan, or Chinese American. In

standard census reports, persons who reported as "Taiwanese" or "Formosan"

are included here with Chinese. In special reports on the Asian or Pacific

Islander population, information on persons who identified themselves as

Taiwanese are shown separately.

Filipino--Includes persons who indicated their race as "Filipino" or

reported entries such as Philipino, Philipine, or Filipino American.

Japanese--Includes persons who indicated their race as "Japanese" and

persons who identified themselves as Nipponese or Japanese American.

Asian Indian--Includes persons who indicated their race as "Asian Indian"

and persons who identified themselves as Bengalese, Bharat, Dravidian, East

Indian, or Goanese.

Korean--Includes persons who indicated their race as "Korean" and persons

who identified themselves as Korean American.

Vietnamese--Includes persons who indicated their race as "Vietnamese" and

persons who identified themselves as Vietnamese American.

Cambodian--Includes persons who provided a write-in response such as

Cambodian or Cambodia.

Hmong--Includes persons who provided a write-in response such as Hmong,

Laohmong, or Mong.

Laotian--Includes persons who provided a write-in response such as Laotian,

Laos, or Lao.

Thai--Includes persons who provided a write-in response such as Thai,

Thailand, or Siamese.

Other Asian--Includes persons who provided a write-in response of

Bangladeshi, Burmese, Indonesian, Pakistani, Sri Lankan,

Amerasian, or Eurasian. See figure 2 for other groups comprising

"Other Asian."

Pacific Islander--Includes persons who indicated their race as "Pacific

Islander" by classifying themselves into one of the following groups or

identifying themselves as one of the Pacific Islander cultural groups

of Polynesian, Micronesian, or Melanesian.

Hawaiian--Includes persons who indicated their race as "Hawaiian" as well

as persons who identified themselves as Part Hawaiian or Native Hawaiian.

Samoan--Includes persons who indicated their race as "Samoan" or persons

who identified themselves as American Samoan or Western Samoan.

Guamanian--Includes persons who indicated their race as "Guamanian" or

persons who identified themselves as Chamorro or Guam.

Other Pacific Islander--Includes persons who provided a write-in response

of a Pacific Islander group such as Tahitian, Northern Mariana Islander,

Palauan, Fijian, or a cultural group such as Polynesian, Micronesian, or

Melanesian. See figure 2 for other groups comprising "Other Pacific

Islander."

Other Race--Includes all other persons not included in the "White,"

"Black," "American Indian, Eskimo, or Aleut," and the "Asian or Pacific

Islander" race categories described above.

Persons reporting in the "Other race" category and providing

write-in entries such as multiracial, multiethnic, mixed, interracial,

Wesort, or a Spanish/Hispanic origin group (such as Mexican, Cuban, or

Puerto Rican) are included here.

Written entries to three categories on the race item--"Indian (Amer.),"

"Other Asian or Pacific Islander (API)," and "Other race"--were reviewed,

edited, and coded by subject matter specialists. (For more information on

the coding operation, see the section below that discusses

"Comparability.")

The written entries under "Indian (Amer.)" and "Other Asian or

Pacific Islander (API)" were reviewed and coded during 100-percent

processing of the 1990 census questionnaires. A substantial portion of

the entries for the "Other race" category also were reviewed,

edited, and coded during the 100-percent processing. The remaining

entries under "Other race" underwent review and coding during

sample processing. Most of the written entries reviewed and coded

during sample processing were those indicating Hispanic origin such as

Mexican, Cuban, or Puerto Rican.

If the race entry for a member of a household was missing on the

questionnaire, race was assigned based upon the reported entries of

race by other household members using specific rules of precedence of

household relationship. For example, if race was missing for the

daughter of the householder, then the race of her mother (as female

householder or female spouse) would be assigned. If there was no female

householder or spouse in the household, the daughter would be assigned

her father's (male householder) race. If race was not reported for

anyone in the household, the race of a householder in a previously

processed household was assigned. This procedure is a variation of the

general imputation procedures described in Appendix C, Accuracy of the

Data.

Limitation of the Data--In the 1980 census, a relatively high proportion

(20 percent) of American Indians did not report any tribal entry in the

race item. Evaluation of the pre-census tests indicated that changes made

for the 1990 race item should improve the reporting of tribes in the rural

areas (especially on reservations) for the 1990 census. The results for

urban areas were inconclusive. Also, the precensus tests indicated that

there may be overreporting of the Cherokee tribe. An evaluation of 1980

census data showed overreporting of Cherokee in urban areas or areas

where the number of American Indians was sparse.

In the 1990 census, respondents sometimes did not fill in a circle or

filled the "Other race" circle and wrote in a response, such as

Arab, Polish, or African American in the shared write-in box for

"Other race" and "Other API" responses. During the automated coding

process, these responses were edited and assigned to the appropriate racial

designation. Also, some Hispanic origin persons did not fill in a circle,

but provided entries such as Mexican or Puerto Rican. These persons were

classified in the "Other race" category during the coding and editing

process. There may be some minor differences between sample data and 100-

percent data because sample processing included additional edits not

included in the 100-percent processing.

Figure 2. Asian or Pacific Islander Groups Reported in the 1990 Census

Asian Pacific Islander

Chinese Hawaiian

Filipino Samoan

Japanese Guamanian

Asian Indian Other Pacific Islander(1)

Korean Carolinian

Vietnamese Fijian

Cambodian Kosraean

Hmong Melanesian(3)

Laotian Micronesian(3)

Thai Northern Mariana Islander

Other Asian(1) Palauan

Bangladeshi Papua New Guinean

Bhutanese Ponapean (Pohnpeian)

Borneo Polynesian(3)

Burmese Solomon Islander

Celebesian Tahitian

Ceram Tarawa Islander

Indochinese Tokelauan

Indonesian Tongan

Iwo-Jiman Trukese (Chuukese)

Javanese Yapese

Malayan Pacific Islander, not specified

Maldivian

Nepali

Okinawan

Pakistani

Sikkim

Singaporean

Sri Lankan

Sumatran

Asian, not specified(2)

---------------------------------------------------------------------------

(1)In some data products, specific groups listed under "Other Asian" or

"Other Pacific Islander" are shown separately. Groups not shown are

tabulated as "All other Asian" or "All other Pacific Islander,"

respectively.

(2)Includes entries such as Asian American, Asian, Asiatic, Amerasian, and

Eurasian.

(3)Polynesian, Micronesian, and Melanesian are Pacific Islander cultural

groups.

Comparability--Differences between the 1990 census and earlier censuses

affect the comparability of data for certain racial groups and American

Indian tribes. The 1990 census was the first census to undertake, on a 100-

percent basis, an automated review, edit, and coding operation for

written responses to the race item. The automated coding system used in

the 1990 census greatly reduced the potential for error associated with

a clerical review. Specialists with a thorough knowledge of the race

subject matter reviewed, edited, coded, and resolved inconsistent or

incomplete responses. In the 1980 census, there was only a limited

clerical review of the race responses on the 100-percent forms with a

full clerical review conducted only on the sample questionnaires.

Another major difference between the 1990 and preceding censuses is the

handling of the write-in responses for the Asian or Pacific Islander

populations. In addition to the nine Asian or Pacific Islander

categories shown on the questionnaire under the spanner "Asian or

Pacific Islander (API)," the 1990 census race item provided a new

residual category, "Other API," for Asian or Pacific Islander

persons who did not report in one of the listed Asian or Pacific

Islander groups. During the coding operation, write-in responses for

"Other API" were reviewed, coded, and assigned to the appropriate

classification. For example, in 1990, a write-in entry of Laotian,

Thai, or Javanese is classified as "Other Asian," while a

write-in entry of Tongan or Fijian is classified as "Other Pacific

Islander." In the 1990 census, these persons were able to identify

as "Other API" in both the 100-percent and sample operations.

In the 1980 census, the nine Asian or Pacific Islander groups were also

listed separately. However, persons not belonging to these nine groups

wrote in their specific racial group under the "Other" race

category. Persons with a written entry such as Laotian, Thai, or

Tongan, were tabulated and published as "Other race" in the 100-

percent processing operation in 1980, but were reclassified as "Other

Asian and Pacific Islander" in 1980 sample tabulations. In 1980

special reports on the Asian or Pacific Islander populations, data were

shown separately for "Other Asian" and "Other Pacific Islander."

The 1970 questionnaire did not have separate race categories for Asian

Indian, Vietnamese, Samoan, and Guamanian. These persons indicated

their race in the "Other" category and later, through the editing

process, were assigned to a specific group. For example, in 1970, Asian

Indians were reclassified as "White," while Vietnamese,

Guamanians, and Samoans were included in the "Other" category.

Another difference between 1990 and preceding censuses is the approach

taken when persons of Spanish/Hispanic origin did not report in a

specific race category but reported as "Other race" or "Other." These

persons commonly provided a write-in entry such as Mexican, Venezuelan, or

Latino. In the 1990 and 1980 censuses, these entries remained in the "Other

race" or "Other" category, respectively. In the 1970 census, most of these

persons were included in the "White" category.

REFERENCE WEEK

The data on labor force status and journey to work were related to

the reference week; that is, the calendar week preceding the date on

which the respondents completed their questionnaires or were

interviewed by enumerators. This week is not the same for all

respondents since the enumeration was not completed in one week. The

occurrence of holidays during the enumeration period could affect the

data on actual hours worked during the reference week, but probably had

no effect on overall measurement of employment status (see the

discussion below on "Comparability").

Comparability--The reference weeks for the 1990 and 1980 censuses differ in

that Passover and Good Friday occurred in the first week of April 1980, but

in the second week of April 1990. Many workers presumably took time off

for those observances. The differing occurrence of these holidays could

affect the comparability of the 1990 and 1980 data on actual hours

worked for some areas if the respective weeks were the reference weeks

for a significant number of persons. The holidays probably did not

affect the overall measurement of employment status since this

information was based on work activity during the entire reference

week.

RESIDENCE IN 1985

The data on residence in 1985 were derived from answers to question

14b, which asked for the State (or foreign country), county, and place

of residence on April 1, 1985, for those persons reporting in question

14a that on that date they lived in a different house than their

current residence. Residence in 1985 is used in conjunction with

location of current residence to determine the extent of residential

mobility of the population and the resulting redistribution of the

population across the various States, metropolitan areas, and regions

of the country.

When no information on residence in 1985 was reported for a person,

information for other family members, if available, was used to assign

a location of residence in 1985. All cases of nonresponse or incomplete

response that were not assigned a previous residence based on

information from other family members were allocated the previous

residence of another person with similar characteristics who provided

complete information.

The tabulation category, "Same house," includes all persons 5 years old and

over who did not move during the 5 years as well as those who had moved but

by 1990 had returned to their 1985 residence. The category, "Different

house in the United States," includes persons who lived in the United

States in 1985 but in a different house or apartment from the one they

occupied on April 1, 1990. These movers are then further subdivided

according to the type of move.

In most tabulations, movers are divided into three groups according to

their 1985 residence: "Different house, same county," "Different county,

same State," and "Different State." The last group may be further

subdivided into region of residence in 1985. The category, "Abroad,"

includes those persons who were residing in a foreign country, Puerto Rico,

or an outlying area of the U.S. in 1985, including members of the Armed

Forces and their dependents. Some tabulations show movers who were residing

in Puerto Rico or an outlying area in 1985 separately from those residing

in other countries.

In tabulations for metropolitan areas, movers are categorized according

to the metropolitan status of their current and previous residences,

resulting in such groups as movers within an MSA/PMSA, movers between

PMSA's, movers from nonmetropolitan areas to MSA/PMSA, and movers from

central cities to the remainder of an MSA/PMSA. In some tabulations,

these categories are further subdivided by size of MSA/PMSA, region of

current or previous residence, or movers within or between central

cities and the remainder of the same or a different MSA/PMSA.

The size categories used in some tabulations for both 1985 and 1990

residence refer to the populations of the MSA/PMSA on April 1, 1990;

that is, at the end of the migration interval.

Some tabulations present data on inmigrants, outmigrants, and net

migration. "Inmigrants" are generally defined as those persons

who entered a specified area by crossing its boundary from some point

outside the area. In some tabulations, movers from abroad are included

in the number of inmigrants; in others, only movers within the United

States are included.

"Outmigrants" are persons who depart from a specific area by

crossing its boundary to a point outside it, but without leaving the

United States. "Net migration" is calculated by subtracting the

number of outmigrants from the number of inmigrants and, depending upon

the particular tabulation, may or may not include movers from abroad.

The net migration for the area is net inmigration if the result was

positive and net outmigration if the result was negative. In the

tabulations, net outmigration is indicated by a minus sign (-).

Inmigrants and outmigrants for States include only those persons who

did not live in the same State in 1985 and 1990; that is, they exclude

persons who moved between counties within the same State. Thus, the sum

of the inmigrants to (or outmigrants from) all counties in any State is

greater than the number of inmigrants to (or outmigrants from) that

State. However, in the case of net migration, the sum of the nets for

all the counties within a State equal the net for the State. In the

same fashion, the net migration for a division or region equals the sum

of the nets for the States comprising that division or region, while

the number of inmigrants and outmigrants for that division or region is

less than the sum of the inmigrants or outmigrants for the individual

States.

The number of persons who were living in a different house in 1985 is

somewhat less than the total number of moves during the 5-year period.

Some persons in the same house at the two dates had moved during the

5-year period but by the time of the census had returned to their 1985

residence. Other persons who were living in a different house had made

one or more intermediate moves. For similar reasons, the number of

persons living in a different county, MSA/PMSA, or State or moving

between nonmetropolitan areas may be understated.

Comparability--Similar questions were asked on all previous censuses

beginning in 1940, except the questions in 1950 referred to residence 1

year earlier rather than 5 years earlier. Although the questions in the

1940 census covered a 5-year period, comparability with that census was

reduced somewhat because of different definitions and categories of

tabulation. Comparability with the 1960 and 1970 census is also somewhat

reduced because nonresponse was not allocated in those earlier censuses.

For the 1980 census, nonresponse was allocated in a manner similar to the

1990 allocation scheme.

SCHOOL ENROLLMENT AND LABOR FORCE STATUS

Tabulation of data on enrollment, educational attainment, and labor

force status for the population 16 to 19 years old allows for

calculation of the proportion of the age group who are not enrolled in

school and not high school graduates or "dropouts" and an

unemployment rate for the "dropout" population. Definitions of

the three topics and descriptions of the census items from which they

were derived are presented in "Educational Attainment," "Employment

Status," and "School Enrollment and Type of School." The published

tabulations include both the civilian and Armed Forces populations, but

labor force status is provided for the civilian population only. Therefore,

the component labor force statuses may not add to the total lines enrolled

in school, high school graduate, and not high school graduate. The

difference is Armed Forces.

Comparability--The tabulation of school enrollment by labor force status is

similar to that published in 1980 census reports. The 1980 census

tabulation included a single data line for Armed Forces; however,

enrollment, attainment, and labor force status data were shown for the

civilian population only. In 1970, a tabulation was included for 16 to 21

year old males not attending school.

SCHOOL ENROLLMENT AND TYPE OF SCHOOL

Data on school enrollment were derived from answers to questionnaire

item 11, which was asked of a sample of persons. Persons were

classified as enrolled in school if they reported attending a

"regular" public or private school or college at any time between

February 1, 1990, and the time of enumeration. The question included

instructions to "include only nursery school, kindergarten,

elementary school, and schooling which would lead to a high school

diploma or a college degree" as regular school. Instructions

included in the 1990 respondent instruction guide, which was mailed

with the census questionnaire, further specified that enrollment in a

trade or business school, company training, or tutoring were not to be

included unless the course would be accepted for credit at a regular

elementary school, high school, or college. Persons who did not answer

the enrollment question were assigned the enrollment status and type of

school of a person with the same age, race or Hispanic origin, and, at

older ages, sex, whose residence was in the same or a nearby area.

Public and Private School--Includes persons who attended school in the

reference period and indicated they were enrolled by marking one of the

questionnaire categories for either "public school, public college" or

"private school, private college." The instruction guide defines

a public school as "any school or college controlled and supported

by a local, county, State, or Federal Government." "Schools

supported and controlled primarily by religious organizations or other

private groups" are defined as private. Persons who filled both the

"public" and "private" circles are edited to the first entry, "public."

Level of School in Which Enrolled--Persons who were enrolled in school were

classified as enrolled in "preprimary school," "elementary or high school,"

or "college" according to their response to question 12 (years of school

completed or highest degree received). Persons who were enrolled and

reported completing nursery school or less were classified as enrolled in

"preprimary school," which includes kindergarten. Similarly, enrolled

persons who had completed at least kindergarten, but not high school, were

classified as enrolled in elementary or high school. Enrolled persons who

reported completing high school or some college or having received a post-

secondary degree were classified as enrolled in "college." Enrolled persons

who reported completing the twelfth grade but receiving "NO DIPLOMA" were

classified as enrolled in high school. (For more information on level of

school, see the discussion under "Educational Attainment.")

Comparability--School enrollment questions have been included in the census

since 1840; grade attended was first asked in 1940; type of school was

first asked in 1960. Before 1940, the enrollment question in various

censuses referred to attendance in the preceding six months or the

preceding year. In 1940, the reference was to attendance in the month

preceding the census, and in the 1950 and subsequent censuses, the question

referred to attendance in the two months preceding the census date.

Until the 1910 census, there were no instructions limiting the kinds of

schools in which enrollment was to be counted. Starting in 1910, the

instructions indicated that attendance at "school, college, or any

educational institution" was to be counted. In 1930 an instruction

to include "night school" was added. In the 1940 instructions,

night school, extension school, or vocational school were included only

if the school was part of the regular school system. Correspondence

school work of any kind was excluded. In the 1950 instructions, the

term "regular school" was introduced, and it was defined as

schooling which "advances a person towards an elementary or high

school diploma or a college, university, or professional school

degree." Vocational, trade, or business schools were excluded unless

they were graded and considered part of a regular school system.

On-the-job training was excluded, as was nursery school. Instruction by

correspondence was excluded unless it was given by a regular school and

counted towards promotion.

In 1960, the question used the term "regular school or college"

and a similar, though expanded, definition of "regular" was

included in the instructions, which continued to exclude nursery

school. Because of the census' use of mailed questionnaires, the 1960

census was the first in which instructions were written for the

respondent as well as enumerators. In the 1970 census, the

questionnaire used the phrase "regular school or college" and

included instructions to "count nursery school, kindergarten, and

schooling which leads to an elementary school certificate, high school

diploma, or college degree." Instructions in a separate document

specified that to be counted as regular school, nursery school must

include instruction as an important and integral phase of its program,

and continued the exclusion of vocational, trade, and business schools.

The 1980 census question was very similar to the 1970 question, but the

separate instruction booklet did not require that nursery school

include substantial instructional content in order to be counted.

The age range for which enrollment data have been obtained and

published has varied over the censuses. Information on enrollment was

recorded for persons of all ages in the 1930 and 1940 and 1970 through

1990; for persons under age 30, in 1950; and for persons age 5 to 34,

in 1960. Most of the published enrollment figures referred to persons

age 5 to 20 in the 1930 census, 5 to 24 in 1940, 5 to 29 in 1950, 5 to

34 in 1960, 3 to 34 in 1970, and 3 years old and over in 1980. This

growth in the age group whose enrollment was reported reflects

increased interest in the number of children in preprimary schools and

in the number of older persons attending colleges and universities.

In the 1950 and subsequent censuses, college students were enumerated

where they lived while attending college, whereas in earlier censuses,

they generally were enumerated at their parental homes. This change

should not affect the comparability of national figures on college

enrollment since 1940; however, it may affect the comparability over

time of enrollment figures at sub-national levels.

Type of school was first introduced in the 1960 census, where a

separate question asked the enrolled persons whether they were in a

"public" or "private" school. Since the 1970 census, the

type of school was incorporated into the response categories for the

enrollment question and the terms were changed to "public,"

"parochial," and "other private." In the 1980 census,

"private, church related" and "private, not church related"

replaced "parochial" and "other private."

Grade of enrollment was first available in the 1940 census, where it

was obtained from responses to the question on highest grade of school

completed. Enumerators were instructed that "for a person still in

school, the last grade completed will be the grade preceding the one in

which he or she was now enrolled." From 1950 to 1980, grade of

enrollment was obtained from the highest grade attended in the two-part

question used to measure educational attainment. (For more information,

see the discussion under "Educational Attainment.") The form of

the question from which level of enrollment was derived in the 1990

census most closely corresponds to the question used in 1940. While

data from prior censuses can be aggregated to provide levels of

enrollment comparable to the 1990 census, 1990 data cannot be

disaggregated to show single grade of enrollment as in previous

censuses.

Data on school enrollment were also collected and published by other

Federal, State, and local government agencies. Where these data were

obtained from administrative records of school systems and institutions

of higher learning, they were only roughly comparable with data from

population censuses and household surveys because of differences in

definitions and concepts, subject matter covered, time references, and

enumeration methods. At the local level, the difference between the

location of the institution and the residence of the student may affect

the comparability of census and administrative data. Differences

between the boundaries of school districts and census geographic units

also may affect these comparisons.

SELF-CARE LIMITATION STATUS

The data on self-care limitation status were derived from answers to

questionnaire item 19b, which was asked of a sample of persons 15 years

old and over. Persons were identified as having a self-care limitation

if they had a health condition that had lasted for 6 or more months and

which made it difficult to take care of their own personal needs, such

as dressing, bathing, or getting around inside the home.

The term "health condition" referred to both physical and mental

conditions. A temporary health problem, such as a broken bone that was

expected to heal normally was not considered a health condition.

Comparability--This was the first time that a question on self-care

limitation was included in the census.

SEX

The data on sex were derived from answers to questionnaire item 3,

which was asked of all persons. For most cases in which sex was not

reported, it was determined by the appropriate entry from the person's

given name and household relationship. Otherwise, sex was imputed

according to the relationship to the householder and the age and

marital status of the person. For more information on imputation, see

Appendix C, Accuracy of the Data.

Sex Ratio--A measure derived by dividing the total number of males by the

total number of females and multiplying by 100.

Comparability--A question on the sex of individuals has been asked of the

total population in every census.

VETERAN STATUS

Data on veteran status, period of military service, and years of

military service were derived from answers to questionnaire item 17,

which was asked of a sample of persons.

Veteran Status--The data on veteran status were derived from responses to

question 17a. For census data products, a "civilian veteran" is a person

16 years old or over who had served (even for a short time) but is not now

serving on active duty in the U.S. Army, Navy, Air Force, Marine Corps,

or the Coast Guard, or who served as a Merchant Marine seaman during

World War II. Persons who served in the National Guard or military

Reserves are classified as veterans only if they were ever called or

ordered to active duty not counting the 4-6 months for initial training

or yearly summer camps. All other civilians 16 years old and over are

classified as nonveterans.

Period of Military Service--Persons who indicated in question 17a that they

had served on active duty (civilian veterans) or were now on active duty

were asked to indicate in question 17b the period or periods in which they

served. Persons serving in at least one wartime period are classified in

their most recent wartime period. For example, persons who served both

during the Korean conflict and the post-Korean peacetime era between

February 1955 and July 1964 are classified in one of the two "Korean

conflict" categories. If the same person had also served during the

Vietnam era, he or she would instead be included in the "Vietnam era

and Korean conflict" category. The responses were edited to

eliminate inconsistencies between reported period(s) of service and the

age of the person and to cancel out reported combinations of periods

containing unreasonable gaps (for example, a person could not serve

during World War I and the Korean conflict without serving during World

War II). Note that the period of service categories shown in this

report are mutually exclusive.

Years of Military Service--Persons who indicated in question 17a that they

had served on active duty (civilian veterans) or were now on active duty

were asked to report the total number of years of active-duty service in

question 17c. The data were edited for consistency with responses to

question 17b (Period of Military Service) and with the age of the person.

Limitation of the Data--There may be a tendency for the following kinds of

persons to report erroneously that they served on active duty in the Armed

Forces: (a) persons who served in the National Guard or military Reserves

but were never called to active duty; (b) civilian employees or volunteers

for the USO, Red Cross, or the Department of Defense (or its predecessor

Departments, War and Navy); and (c) employees of the Merchant Marine or

Public Health Service. There may also be a tendency for persons to

erroneously round up months to the nearest year in question 17c (for

example, persons with 1 year 8 months of active duty military service

may mistakenly report "2 years").

Comparability--Since census data on veterans were based on self-reported

responses, they may differ from data from other sources such as

administrative records of the Department of Defense. Census data may also

differ from Veterans Administration data on the benefits-eligible

population, since factors determining eligibility for veterans benefits

differ from the rules for classifying veterans in the census.

The wording of the question on veteran status (17a) for 1990 was

expanded from the veteran/not veteran question in 1980 to include

questions on current active duty status and service in the military

Reserves and the National Guard. The expansion was intended to clarify

the appropriate response for persons in the Armed Forces and for

persons who served in the National Guard or military Reserve units

only. For the first time in a census, service during World War II as a

Merchant Marine Seaman was considered active-duty military service and

persons with such service were counted as veterans. An additional

period of military service, "September 1980 or later" was added

in 1990. As in 1970 and 1980, persons reporting more than one period of

service are shown in the most recent wartime period of service

category. Question 17c (Years of Military Service) was new for 1990.

WORK DISABILITY STATUS

The data on work disability were derived from answers to questionnaire item

18, which was asked of a sample of persons 15 years old and over. Persons

were identified as having a work disability if they had a health condition

that had lasted for 6 or more months and which limited the kind or amount

of work they could do at a job or business. A person was limited in the

kind of work he or she could do if the person had a health condition which

restricted his or her choice of jobs. A person was limited in the amount of

work if he or she was not able to work full-time. Persons with a work

disability were further classified as "Prevented from working" or "Not

prevented from working."

The term "health condition" referred to both physical and mental

conditions. A temporary health problem, such as a broken bone that was

expected to heal normally, was not considered a health condition.

Comparability--The wording of the question on work disability

was the same in 1990 as in 1980. Information on work disability was

first collected in 1970. In that census, the work disability question

did not contain a clause restricting the definition of disability to

limitations caused by a health condition that had lasted 6 or more

months; however, it did contain a separate question about the duration

of the disability.

WORK STATUS IN 1989

The data on work status in 1989 were derived from answers to

questionnaire item 31, which was asked of a sample of persons. Persons

16 years old and over who worked 1 or more weeks according to the

criteria described below are classified as "Worked in 1989." All

other persons 16 years old and over are classified as "Did not work

in 1989." Some tabulations showing work status in 1989 include 15

year olds; these persons, by definition, are classified as "Did not

work in 1989."

Weeks Worked in 1989

The data on weeks worked in 1989 were derived from responses to

questionnaire item 31b. Question 31b (Weeks Worked in 1989) was asked

of persons 16 years old and over who indicated in question 31a that

they worked in 1989.

The data pertain to the number of weeks during 1989 in which a person

did any work for pay or profit (including paid vacation and paid sick

leave) or worked without pay on a family farm or in a family business.

Weeks of active service in the Armed Forces are also included.

Usual Hours Worked Per Week Worked in 1989

The data on usual hours worked per week worked in 1989 were derived

from answers to questionnaire item 31c. This question was asked of

persons 16 years old and over who indicated that they worked in 1989.

The data pertain to the number of hours a person usually worked during

the weeks worked in 1989. The respondent was to report the number of

hours worked per week in the majority of the weeks he or she worked in

1989. If the hours worked per week varied considerably during 1989, the

respondent was to report an approximate average of the hours worked per

week. The statistics on usual hours worked per week in 1989 are not

necessarily related to the data on actual hours worked during the

census reference week (question 21b).

Persons 16 years old and over who reported that they usually worked 35

or more hours each week during the weeks they worked are classified as

"Usually worked full time;" persons who reported that they

usually worked 1 to 34 hours are classified as "Usually worked part

time."

Year-Round Full-Time Workers--All persons 16 years old and over who usually

worked 35 hours or more per week for 50 to 52 weeks in 1989.

Number of Workers in Family in 1989--The term "worker" as used for these

data is defined based on the criteria for Work Status in 1989.

Limitation of the Data--It is probable that the number of persons who

worked in 1989 and the number of weeks worked are understated since there

was some tendency for respondents to forget intermittent or short periods

of employment or to exclude weeks worked without pay. There may also be a

tendency for persons not to include weeks of paid vacation among their

weeks worked; one result may be that the census figures may understate the

number of persons who worked "50 to 52 weeks."

Comparability--The data on weeks worked collected in the 1990 census were

comparable with data from the 1980, 1970, and 1960 censuses, but may not be

entirely comparable with data from the 1940 and 1950 censuses. Since

the 1960 census, two separate questions have been used to obtain this

information. The first identified persons with any work experience

during the year and, thus, indicated those persons for whom the

questions on number of weeks worked applied. In 1940 and 1950, however,

the questionnaires contained only a single question on number of weeks

worked.

In 1970, persons responded to the question on weeks worked by

indicating one of six weeks-worked intervals. In 1980 and 1990, persons

were asked to enter the specific number of weeks they worked.

YEAR OF ENTRY

The data on year of entry were derived from answers to questionnaire

item 10, which was asked of a sample of persons. The question, "When

did this person come to the United States to stay?" was asked of

persons who indicated in the question on citizenship that they were not

born in the United States. (For more information, see the discussion

under "Citizenship.")

The 1990 census questions, tabulations, and census data products about

citizenship and year of entry include no reference to immigration. All

persons who were born and resided outside the United States before

becoming residents of the United States have a date of entry. Some of

these persons are U.S. citizens by birth (e.g., persons born in Puerto

Rico or born abroad of American parents). To avoid any possible

confusion concerning the date of entry of persons who are U.S. citizens

by birth, the term, "year of entry" is used in this report

instead of the term "year of immigration."

Limitation of the Data--The census questions on nativity, citizenship, and

year of entry were not designed to measure the degree of permanence of

residence in the United States. The phrase, "to stay" was used to obtain

the year in which the person became a resident of the United States.

Although the respondent was directed to indicate the year he or she entered

the country "to stay," it was difficult to ensure that respondents

interpreted the phrase correctly.

Comparability--A question on year of entry, (alternately called "year of

immigration") was asked in each decennial census from 1890 to 1930,

1970, and 1980. In 1980, the question on year of entry included six

arrival time intervals. The number of arrival intervals was expanded to

ten in 1990. In 1980, the question on year of entry was asked only of

the foreign-born population. In 1990, all persons who responded to the

long-form questionnaire and were not born in the United States were to

complete the question on year of entry.

HOUSING CHARACTERISTICS

LIVING QUARTERS

Living quarters are classified as either housing units or group

quarters. (For more information, see the discussion of "Group

Quarters" under Population Characteristics.) Usually, living

quarters are in structures intended for residential use (for example, a

one-family home, apartment house, hotel or motel, boarding house, or

mobile home). Living quarters also may be in structures intended for

nonresidential use (for example, the rooms in a warehouse where a guard

lives), as well as in places such as tents, vans, shelters for the

homeless, dormitories, barracks, and old railroad cars.

Housing Units--A housing unit is a house, an apartment, a mobile home or

trailer, a group of rooms or a single room occupied as separate living

quarters or, if vacant, intended for occupancy as separate living quarters.

Separate living quarters are those in which the occupants live and eat

separately from any other persons in the building and which have direct

access from outside the building or through a common hall.

The occupants may be a single family, one person living alone, two or

more families living together, or any other group of related or

unrelated persons who share living arrangements. For vacant units, the

criteria of separateness and direct access are applied to the intended

occupants whenever possible. If that information cannot be obtained,

the criteria are applied to the previous occupants.

Both occupied and vacant housing units are included in the housing unit

inventory, except that recreational vehicles, boats, vans, tents,

railroad cars, and the like are included only if they are occupied as

someone's usual place of residence. Vacant mobile homes are included

provided they are intended for occupancy on the site where they stand.

Vacant mobile homes on dealers' sales lots, at the factory, or in

storage yards are excluded from the housing inventory.

If the living quarters contains nine or more persons unrelated to the

householder or person in charge (a total of at least 10 unrelated

persons), it is classified as group quarters. If the living quarters

contains eight or fewer persons unrelated to the householder or person

in charge, it is classified as a housing unit.

Occupied Housing Units--A housing unit is classified as occupied if it is

the usual place of residence of the person or group of persons living in it

at the time of enumeration, or if the occupants are only temporarily

absent; that is, away on vacation or business. If all the persons staying

in the unit at the time of the census have their usual place of residence

elsewhere, the unit is classified as vacant. A household includes all the

persons who occupy a housing unit as their usual place of residence. By

definition, the count of occupied housing units for 100-percent

tabulations is the same as the count of households or householders. In

sample tabulations, the counts of household and occupied housing units

may vary slightly because of different sample weighting methods.

Vacant Housing Units--A housing unit is vacant if no one is living in it at

the time of enumeration, unless its occupants are only temporarily absent.

Units temporarily occupied at the time of enumeration entirely by persons

who have a usual residence elsewhere also are classified as vacant. (For

more information, see discussion under "Usual Home Elsewhere.")

New units not yet occupied are classified as vacant housing units if

construction has reached a point where all exterior windows and doors

are installed and final usable floors are in place. Vacant units are

excluded if they are open to the elements; that is, the roof, walls,

windows, and/or doors no longer protect the interior from the elements,

or if there is positive evidence (such as a sign on the house or in the

block) that the unit is condemned or is to be demolished. Also excluded

are quarters being used entirely for nonresidential purposes, such as a

store or an office, or quarters used for the storage of business

supplies or inventory, machinery, or agricultural products.

Hotels, Motels, Rooming Houses, Etc.--Occupied rooms or suites of rooms in

hotels, motels, and similar places are classified as housing units only

when occupied by permanent residents; that is, persons who consider the

hotel as their usual place of residence or have no usual place of residence

elsewhere. Vacant rooms or suites of rooms are classified as housing units

only in those hotels, motels, and similar places in which 75 percent or

more of the accommodations are occupied by permanent residents.

If any of the occupants in a rooming or boarding house live and eat

separately from others in the building and have direct access, their

quarters are classified as separate housing units.

Staff Living Quarters--The living quarters occupied by staff personnel

within any group quarters are separate housing units if they satisfy the

housing unit criteria of separateness and direct access; otherwise, they

are considered group quarters.

Comparability--The first Census of Housing in 1940 established the

"dwelling unit" concept. Although the term became "housing unit" and the

definition has been modified slightly in succeeding censuses, the 1990

definition is essentially comparable to previous censuses. There was no

change in the housing unit definition between 1980 and 1990.

ACREAGE

The data on acreage were obtained from questionnaire items H5a and

H19a. Question H5a was asked at all occupied and vacant one-family

houses and mobile homes. Question H19a was asked on a sample basis at

occupied and vacant one-family houses and mobile homes.

Question H5a asks whether the house or mobile home is located on a

place of 10 or more acres. The intent of this item is to exclude

owner-occupied and renter-occupied one-family houses on 10 or more

acres from the specified owner- and renter-occupied universes for value

and rent tabulations.

Question H19a provides data on whether the unit is located on less than

1 acre. The main purpose of this item, in conjunction with question

H19b on agricultural sales, is to identify farm units. (For more

information, see discussion under "Farm Residence.")

For both items, the land may consist of more than one tract or plot.

These tracts or plots are usually adjoining; however, they may be

separated by a road, creek, another piece of land, etc.

Comparability--

Question H5a is similar to that asked in 1970 and 1980. This item was

asked for the first time of mobile home occupants in 1990. Question

H19a is an abbreviated form of a question asked on a sample basis in

1980. In previous censuses, information on city or suburban lot and

number of acres was obtained also.

AGRICULTURAL SALES

Data on the sales of agricultural crops were obtained from

questionnaire item H19b, which was asked on a sample basis at occupied

one-family houses and mobile homes located on lots of 1 acre or more.

Data for this item exclude units on lots of less than 1 acre, units

located in structures containing 2 or more units, and all vacant units.

This item refers to the total amount (before taxes and expenses)

received in 1989 from the sale of crops, vegetables, fruits, nuts,

livestock and livestock products, and nursery and forest products,

produced on "this property." Respondents new to a unit were asked

to estimate total agricultural sales in 1989 even if some portion of

the sales had been made by other occupants of the unit.

This item is used mainly to classify housing units as farm or nonfarm

residences, not to provide detailed information on the sale of

agricultural products. Detailed information on the sale of agricultural

products is provided by the Census Bureau's Census of Agriculture

(Factfinder for the Nation: Agricultural Statistics, Bureau

of the Census, 1989). (For more information, see the discussion under

"Farm Residence.")

BEDROOMS

The data on bedrooms were obtained from questionnaire item H9, which

was asked at both occupied and vacant housing units. This item was

asked on a sample basis. The number of bedrooms is the count of rooms

designed to be used as bedrooms; that is, the number of rooms that

would be listed as bedrooms if the house or apartment were on the

market for sale or for rent. Included are all rooms intended to be used

as bedrooms even if they currently are being used for some other

purpose. A housing unit consisting of only one room, such as a one-room

efficiency apartment, is classified, by definition, as having no

bedroom.

Comparability--Data on bedrooms have been collected in every census since

1960. In 1970 and 1980, data for bedrooms were shown only for year-round

units. In past censuses, a room was defined as a bedroom if it was used

mainly for sleeping even if also used for other purposes. Rooms that were

designed to be used as bedrooms but used mainly for other purposes were

not considered to be bedrooms. A distribution of housing units by

number of bedrooms calculated from data collected in a 1986 test showed

virtually no differences in the two versions except in the two bedroom

category, where the previous "use" definition showed a slightly

lower proportion of units.

BOARDED-UP STATUS

Boarded-up status was obtained from questionnaire item C2 and was

determined for all vacant units. Boarded-up units have windows and

doors covered by wood, metal, or masonry to protect the interior and to

prevent entry into the building. A single-unit structure, a unit in a

multi-unit structure, or an entire multi-unit structure may be

boarded-up in this way. For certain census data products, boarded-up

units are shown only for units in the "Other vacant" category. A

unit classified as "Usual home elsewhere" can never be boarded

up. (For more information, see the discussion under "Usual Home

Elsewhere.")

Comparability--This item was first asked in the 1980 census and was shown

only for year-round vacant housing units. In 1990, data are shown for all

vacant housing units.

BUSINESS ON PROPERTY

The data for business on property were obtained from questionnaire

item H5b, which was asked at all occupied and vacant one-family houses

and mobile homes. This question is used to exclude owner-occupied

one-family houses with business or medical offices on the property from

certain statistics on financial characteristics.

A business must be easily recognizable from the outside. It usually

will have a separate outside entrance and have the appearance of a

business, such as a grocery store, restaurant, or barber shop. It may

be either attached to the house or mobile home or be located elsewhere

on the property. Those housing units in which a room is used for

business or professional purposes and have no recognizable alterations

to the outside are not considered as having a business.

Medical offices are considered businesses for tabulation purposes.

Comparability--Data on business on property have been collected since 1940.

CONDOMINIUM FEE

The data on condominium fee were obtained from questionnaire item

H25, which was asked at owner-occupied condominiums. This item was

asked on a sample basis. A condominium fee normally is charged monthly

to the owners of the individual condominium units by the condominium

owners association to cover operating, maintenance, administrative, and

improvement costs of the common property (grounds, halls, lobby,

parking areas, laundry rooms, swimming pool, etc.) The costs for

utilities and/or fuels may be included in the condominium fee if the

units do not have separate meters.

Data on condominium fees may include real estate tax and/or insurance

payments for the common property, but do not include real estate taxes

or fire, hazard, and flood insurance for the individual unit already

reported in questions H21 and H22.

Amounts reported were the regular monthly payment, even if paid by

someone outside the household or remain unpaid. Costs were estimated as

closely as possible when exact costs were not known.

The data from this item were added to payments for mortgages (both

first and junior mortgages and home equity loans); real estate taxes;

fire, hazard, and flood insurance payments; and utilities and fuels to

derive "Selected Monthly Owner Costs" and "Selected Monthly

Owner Costs as a Percentage of Household Income in 1989" for

condominium owners.

Comparability--This is a new item in 1990.

CONDOMINIUM STATUS

The data on condominium housing units were obtained from

questionnaire item H18, which was asked on a sample basis at both

occupied and vacant housing units. Condominium is a type of ownership

that enables a person to own an apartment or house in a development of

similarly owned units and to hold a common or joint ownership in some

or all of the common areas and facilities such as land, roof, hallways,

entrances, elevators, swimming pool, etc. Condominiums may be

single-family houses as well as units in apartment buildings. A

condominium unit need not be occupied by the owner to be counted as

such. A unit classified as "mobile home or trailer" or

"other" (see discussion under "Units in Structure") cannot

be a condominium unit.

Limitation of the Data--Testing done prior to the 1980 and 1990 censuses

indicated that the number of condominiums may be slightly overstated.

Comparability--In 1970, condominiums were grouped together with cooperative

housing units, and the data were reported only for owner-occupied

cooperatives and condominiums. Beginning in 1980, the census identified all

condominium units and the data were shown for renter-occupied and vacant

year-round condominiums as well as owner occupied. In 1970 and 1980, the

question on condominiums was asked on a 100-percent basis. In 1990, it was

asked on a sample basis.

CONTRACT RENT

The data on contract rent (also referred to as "rent asked" for vacant

units) were obtained from questionnaire item H7a, which was asked at all

occupied housing units that were rented for cash rent and all vacant

housing units that were for rent at the time of enumeration.

Housing units that are renter occupied without payment of cash rent are

shown separately as "No cash rent" in census data products. The

unit may be owned by friends or relatives who live elsewhere and who

allow occupancy without charge. Rent-free houses or apartments may be

provided to compensate caretakers, ministers, tenant farmers,

sharecroppers, or others.

Contract rent is the monthly rent agreed to or contracted for,

regardless of any furnishings, utilities, fees, meals, or services that

may be included. For vacant units, it is the monthly rent asked for the

rental unit at the time of enumeration.

If the contract rent includes rent for a business unit or for living

quarters occupied by another household, the respondent was instructed

to report that part of the rent estimated to be for his or her unit

only. Respondents were asked to report rent only for the housing unit

enumerated and to exclude any rent paid for additional units or for

business premises.

If a renter pays rent to the owner of a condominium or cooperative, and

the condominium fee or cooperative carrying charge is also paid by the

renter to the owner, the respondent was instructed to include the fee

or carrying charge.

If a renter receives payments from lodgers or roomers who are listed as

members of the household, the respondent was instructed to report the

rent without deduction for any payments received from the lodgers or

roomers. The respondent was instructed to report the rent agreed to or

contracted for even if paid by someone else such as friends or

relatives living elsewhere, or a church or welfare agency.

In some tabulations, contract rent is presented for all renter-occupied

housing units, as well as specified renter-occupied and vacant-for-rent

units. Specified renter-occupied and specified vacant-for-rent units

exclude one-family houses on 10 or more acres. (For more information on

rent, see the discussion under "Gross Rent.")

Median and Quartile Contract Rent--The median divides the rent distribution

into two equal parts.

Quartiles divide the rent distribution into four equal parts. In

computing median and quartile contract rent, units reported as "No

cash rent" are excluded. Median and quartile rent calculations are

rounded to the nearest whole dollar. (For more information on medians

and quartiles, see the discussion under "Derived Measures.")

Aggregate Contract Rent--To calculate aggregate contract rent, the amount

assigned for the category "Less than $80" is $50. The amount assigned to

the category "$1,000 or more" is $1,250. Mean contract rent is

rounded to the nearest whole dollar. (For more information on

aggregates and means, see the discussion under "Derived Measures.")

Limitation of the Data--In the 1970 and 1980 censuses, contract rent for

vacant units had high allocation rates, about 35 percent.

Comparability--Data on this item have been collected since 1930. For 1990,

quartiles were added because the range of rents and values in the United

States has increased in recent years. Upper and lower quartiles can be used

to note large rent and value differences among various geographic areas.

DURATION OF VACANCY

The data for duration of vacancy (also referred to as "months

vacant") were obtained from questionnaire item D, which was

completed by census enumerators. The statistics on duration of vacancy

refer to the length of time (in months and years) between the date the

last occupants moved from the unit and the time of enumeration. The

data, therefore, do not provide a direct measure of the total length of

time units remain vacant.

For newly constructed units which have never been occupied, the

duration of vacancy is counted from the date construction was

completed. For recently converted or merged units, the time is reported

from the date conversion or merger was completed. Units occupied by an

entire household with a usual home elsewhere are assigned to the

"Less than 1 month" interval.

Comparability--Similar data have been collected since 1960. In 1970 and

1980, these data were shown only for year-round vacant housing units. In

1990, these data are shown for all vacant housing units.

FARM RESIDENCE

The data on farm residence were obtained from questionnaire items

H19a and H19b. An occupied one-family house or mobile home is

classified as a farm residence if: (1) the housing unit is located on a

property of 1 acre or more, and (2) at least $1,000 worth of

agricultural products were sold from the property in 1989. Group

quarters and housing units that are in multi-unit buildings or vacant

are not included as farm residences.

A one-family unit occupied by a tenant household paying cash rent for

land and buildings is enumerated as a farm residence only if sales of

agricultural products from its yard (as opposed to the general property

on which it is located) amounted to at least $1,000 in 1989. A

one-family unit occupied by a tenant household that does not pay cash

rent is enumerated as a farm residence if the remainder of the farm

(including its yard) qualifies as a farm.

Farm residence is provided as an independent data item only for housing

units located in rural areas. It may be derived for housing units in

urban areas from the data items on acreage and sales of agricultural

products on the public-use microdata sample (PUMS) files. (For more

information on PUMS, see Appendix F, Data Products and User

Assistance.)

The farm population consists of persons in households living in farm

residences. Some persons who are counted on a property classified as a

farm (including in some cases farm workers) are excluded from the farm

population. Such persons include those who reside in multi-unit

buildings or group quarters.

Comparability--These are the same criteria that were used to define a farm

residence in 1980. In 1960 and 1970, a farm was defined as a place of 10 or

more acres with at least $50 worth of agricultural sales or a place of less

than 10 acres with at least $250 worth of agricultural sales. Earlier

censuses used other definitions. Note that the definition of a farm

residence differs from the definition of a farm in the Census of

Agriculture (Factfinder for the Nation: Agricultural Statistics, Bureau of

the Census, 1989).

GROSS RENT

Gross rent is the contract rent plus the estimated average monthly

cost of utilities (electricity, gas, and water) and fuels (oil, coal,

kerosene, wood, etc.) if these are paid for by the renter (or paid for

the renter by someone else). Gross rent is intended to eliminate

differentials which result from varying practices with respect to the

inclusion of utilities and fuels as part of the rental payment. The

estimated costs of utilities and fuels are reported on a yearly basis

but are converted to monthly figures for the tabulations. Renter units

occupied without payment of cash rent are shown separately as "No

cash rent" in the tabulations. Gross rent is calculated on a sample

basis.

Comparability--Data on gross rent have been collected since 1940 for

renter-occupied housing units. In 1980, costs for electricity and gas were

collected as average monthly costs. In 1990, all utility and fuel costs

were collected as yearly costs and divided by 12 to provide an average

monthly cost.

GROSS RENT AS A PERCENTAGE OF HOUSEHOLD INCOME IN 1989

Gross rent as a percentage of household income in 1989 is a computed

ratio of monthly gross rent to monthly household income (total

household income in 1989 divided by 12). The ratio was computed

separately for each unit and was rounded to the nearest whole

percentage. Units for which no cash rent is paid and units occupied by

households that reported no income or a net loss in 1989 comprise the

category "Not computed." This item is calculated on a sample

basis.

HOUSE HEATING FUEL

The data on house heating fuel were obtained from questionnaire item

H14, which was asked at occupied housing units. This item was asked on

a sample basis. The data show the type of fuel used most to heat the

house or apartment.

Utility Gas--Includes gas piped through underground pipes from a central

system to serve the neighborhood.

Bottled, Tank, or LP Gas--Includes liquid propane gas stored in bottles or

tanks which are refilled or exchanged when empty.

Fuel Oil, Kerosene, Etc.--Includes fuel oil, kerosene, gasoline, alcohol,

and other combustible liquids.

Wood--Includes purchased wood, wood cut by household members on their

property or elsewhere, driftwood, sawmill or construction scraps, or

the like.

Solar Energy--Includes heat provided by sunlight which is collected,

stored, and actively distributed to most of the rooms.

Other Fuel--Includes all other fuels not specified elsewhere.

No Fuel Used--Includes units that do not use any fuel or that do not have

heating equipment.

Comparability--Data on house heating fuel have been collected since 1940.

The category, "Solar energy" is new for 1990.

INSURANCE FOR FIRE, HAZARD, AND FLOOD

The data on fire, hazard, and flood insurance were obtained from

questionnaire item H22, which was asked at a sample of owner-occupied

one-family houses, condominiums, and mobile homes. The statistics for

this item refer to the annual premium for fire, hazard, and flood

insurance on the property (land and buildings); that is, policies that

protect the property and its contents against loss due to damage by

fire, lightning, winds, hail, flood, explosion, and so on.

Liability policies are included only if they are paid with the fire,

hazard, and flood insurance premiums and the amounts for fire, hazard,

and flood cannot be separated. Premiums are included even if paid by

someone outside the household or remain unpaid. When premiums are paid

on other than a yearly basis, the premiums are converted to a yearly

basis.

The payment for fire, hazard, and flood insurance is added to payments

for real estate taxes, utilities, fuels, and mortgages (both first and

junior mortgages and home equity loans) to derive "Selected Monthly

Owner Costs" and "Selected Monthly Owner Costs as a Percentage of

Household Income in 1989."

A separate question (H23d) determines whether insurance premiums are

included in the mortgage payment to the lender(s). This makes it

possible to avoid counting these premiums twice in the computations.

Comparability--Data on payment for fire and hazard insurance were collected

for the first time in 1980. Flood insurance was not specifically mentioned

in the wording of the question in 1980. The question was asked only at

owner-occupied one-family houses. Excluded were mobile homes,

condominiums, houses with a business or medical office on the property,

houses on 10 or more acres, and housing units in multi-unit buildings.

In 1990, the question was asked of all one-family owner-occupied

houses, including houses on 10 or more acres. It also was asked at

mobile homes, condominiums, and one-family houses with a business or

medical office on the property.

KITCHEN FACILITIES

Data on kitchen facilities were obtained from questionnaire item

H11, which was asked at both occupied and vacant housing units. A unit

has complete kitchen facilities when it has all of the following: (1)

an installed sink with piped water, (2) a range, cook top and

convection or microwave oven, or cookstove, and (3) a refrigerator. All

kitchen facilities must be located in the structure. They need not be

in the same room. Portable cooking equipment is not considered a range

or cookstove. An ice box is not considered to be a refrigerator.

Comparability--Data on complete kitchen facilities were collected for the

first time in 1970. Earlier censuses collected data on individual

components, such as kitchen sink and type of refrigeration equipment. In

1970 and 1980, data for kitchen facilities were shown only for year-round

units. In 1990, data are shown for all housing units.

MEALS INCLUDED IN RENT

The data on meals included in the rent were obtained from

questionnaire item H7b, which was asked of all occupied housing units

that were rented for cash and all vacant housing units that were for

rent at the time of enumeration.

The statistics on meals included in rent are presented for specified

renter-occupied and specified vacant-for-rent units. Specified

renter-occupied and specified vacant-for-rent units exclude one-family

houses on 10 or more acres. (For more information, see the discussion under

"Contract Rent.")

Comparability--This is a new item in 1990. It is intended to measure

"congregate" housing, which generally is considered to be housing

units where the rent includes meals and other services, such as

transportation to shopping and recreation.

MOBILE HOME COSTS

The data on mobile home costs were obtained from questionnaire item

H26, which was asked at owner-occupied mobile homes. This item was

asked on a sample basis.

These data include the total yearly costs for personal property taxes,

land or site rent, registration fees, and license fees on all

owner-occupied mobile homes. The instructions are to not include real

estate taxes already reported in question H21.

Costs are estimated as closely as possible when exact costs are not

known. Amounts are the total for an entire 12-month billing period,

even if they are paid by someone outside the household or remain

unpaid.

The data from this item are added to payments for mortgages, real

estate taxes, fire, hazard, and flood insurance payments, utilities,

and fuels to derive selected monthly owner costs for mobile homes

owners.

Comparability--This item is new for 1990.

MORTGAGE PAYMENT

The data on mortgage payment were obtained from questionnaire item

H23b, which was asked at owner occupied one-family houses,

condominiums, and mobile homes. This item was asked on a sample basis.

Question H23b provides the regular monthly amount required to be paid

the lender for the first mortgage (deed of trust, contract to purchase,

or similar debt) on the property. Amounts are included even if the

payments are delinquent or paid by someone else. The amounts reported

are included in the computation of "Selected Monthly Owner Costs"

and "Selected Monthly Owner Costs as a Percentage of Household

Income in 1989" for units with a mortgage.

The amounts reported include everything paid to the lender including

principal and interest payments, real estate taxes, fire, hazard, and

flood insurance payments, and mortgage insurance premiums. Separate

questions determine whether real estate taxes and fire, hazard, and

flood insurance payments are included in the mortgage payment to the

lender. This makes it possible to avoid counting these components twice

in the computation of "Selected Monthly Owner Costs."

Comparability--Information on mortgage payment was collected for the first

time in 1980. It was collected only at owner-occupied one-family houses.

Excluded were mobile homes, condominiums, houses with a business or

medical office on the property, one-family houses on 10 or more acres,

and housing units in multi-unit buildings. In 1990, the questions on

monthly mortgage payments were asked of all owner-occupied one-family

houses, including one-family houses on 10 or more acres. They were also

asked at mobile homes, condominiums, and one-family houses with a

business or medical office.

The 1980 census obtained total regular monthly mortgage payments,

including payments on second or junior mortgages, from a single

question. Two questions were used in 1990; one for regular monthly

payments on first mortgages, and one for regular monthly payments on

second or junior mortgages or home equity loans. (For more information,

see the discussion under "Second or Junior Mortgage Payment.")

MORTGAGE STATUS

The data on mortgage status were obtained from questionnaire items

H23a and H24a, which were asked at owner-occupied one-family houses,

condominiums, and mobile homes. "Mortgage" refers to all forms of

debt where the property is pledged as security for repayment of the

debt. It includes such debt instruments as deeds of trust, trust deeds,

contracts to purchase, land contracts, junior mortgages and home equity

loans.

A mortgage is considered a first mortgage if it has prior claim over

any other mortgage or if it is the only mortgage on the property. All

other mortgages, (second, third, etc.) are considered junior mortgages.

A home equity loan is generally a junior mortgage. If no first mortgage

is reported, but a junior mortgage or home equity loan is reported,

then the loan is considered a first mortgage.

In most census data products, the tabulations for "Selected Monthly

Owner Costs" and "Selected Monthly Owner Costs as a Percentage of

Household Income in 1989" usually are shown separately for units

"with a mortgage" and for units "not mortgaged." The

category "not mortgaged" is comprised of housing units owned free

and clear of debt.

Comparability--A question on mortgage status was included in the 1940 and

1950 censuses, but not in the 1960 and 1970 censuses. The item was

reinstated in 1980 along with a separate question dealing with the

existence of second or junior mortgages. In 1980, the mortgage status

questions were asked at owner-occupied one-family houses on less than

10 acres. Excluded were mobile homes, condominiums, houses with a

business or medical office, houses on 10 or more acres, and housing

units in multi-unit buildings. In 1990, the questions were asked of all

one-family owner-occupied housing units, including houses on 10 or more

acres. They were also asked at mobile homes, condominiums, and houses

with a business or medical office.

PERSONS IN UNIT

This item is based on the 100-percent count of persons in occupied

housing units. All persons occupying the housing unit are counted,

including the householder, occupants related to the householder, and

lodgers, roomers, boarders, and so forth.

The data on "persons in unit" show the number of housing units

occupied by the specified number of persons. The phrase "persons in

unit" is used for housing tabulations, "persons in households"

for population items. Figures for "persons in unit" match those

for "persons in household" for 100-percent data products. In

sample products, they may differ because of the weighting process.

Median Persons in Unit--In computing median persons in unit, a whole number

is used as the midpoint of an interval; thus, a unit with 4 persons is

treated as an interval ranging from 3.5 to 4.5 persons. Median persons is

rounded to the nearest hundredth. (For more information on medians, see the

discussion under "Derived Measures.")

Persons in Occupied Housing Units--This is the total population minus those

persons living in group quarters. "Persons per occupied housing unit" is

computed by dividing the population living in housing units by the number

of occupied housing units.

PERSONS PER ROOM

"Persons per room" is obtained by dividing the number of

persons in each occupied housing unit by the number of rooms in the

unit. Persons per room is rounded to the nearest hundredth. The figures

shown refer, therefore, to the number of occupied housing units having

the specified ratio of persons per room.

Mean Persons Per Room--This is computed by dividing persons in housing

units by the aggregate number of rooms. This is intended to provide a

measure of utilization. A higher mean may indicate a greater degree of

utilization or crowding; a low mean may indicate under-utilization. (For

more information on means, see the discussion under "Derived Measures.")

PLUMBING FACILITIES

The data on plumbing facilities were obtained from questionnaire

item H10, which was asked at both occupied and vacant housing units.

This item was asked on a sample basis. Complete plumbing facilities

include hot and cold piped water, a flush toilet, and a bathtub or

shower. All three facilities must be located inside the house,

apartment, or mobile home, but not necessarily in the same room.

Housing units are classified as lacking complete plumbing facilities

when any of the three facilities are not present.

Comparability--The 1990 data on complete plumbing facilities are not

strictly comparable with the 1980 data. In 1980, complete plumbing

facilities were defined as hot and cold piped water, a bathtub or shower,

and a flush toilet in the housing unit for the exclusive use of the

residents of that unit. In 1990, the Census Bureau dropped the requirement

of exclusive use from the definition of complete plumbing facilities. Of

the 2.3 million year-round housing units classified in 1980 as lacking

complete plumbing for exclusive use, approximately 25 percent of these

units had complete plumbing but the facilities were also used by

members of another household. From 1940 to 1970, separate and more

detailed questions were asked on piped water, bathing, and toilet

facilities. In 1970 and 1980, the data on plumbing facilities were

shown only for year-round units.

POVERTY STATUS OF HOUSEHOLDS IN 1989

The data on poverty status of households were derived from answers

to the income questions. The income items were asked on a sample basis.

Households are classified below the poverty level when the total 1989

income of the family or of the nonfamily householder is below the

appropriate poverty threshold. The income of persons living in the

household who are unrelated to the householder is not considered when

determining the poverty status of a household, nor does their presence

affect the household size in determining the appropriate poverty

threshold. The poverty thresholds vary depending upon three criteria:

size of family, number of children, and age of the family householder

or unrelated individual for one and two-persons households. (For more

information, see the discussion of "Poverty Status in 1989" and "Income in

1989" under Population Characteristics.)

REAL ESTATE TAXES

The data on real estate taxes were obtained from questionnaire item

H21, which was asked at owner-occupied one-family houses, condominiums,

and mobile homes. The statistics from this question refer to the total

amount of all real estate taxes on the entire property (land and

buildings) payable in 1989 to all taxing jurisdictions, including

special assessments, school taxes, county taxes, and so forth.

Real estate taxes include State, local, and all other real estate taxes

even if delinquent, unpaid, or paid by someone who is not a member of

the household. However, taxes due from prior years are not included. If

taxes are paid on other than a yearly basis, the payments are converted

to a yearly basis.

The payment for real estate taxes is added to payments for fire,

hazard, and flood insurance; utilities and fuels; and mortgages (both

first and junior mortgages and home equity loans) to derive

"Selected Monthly Owner Costs" and "Selected Monthly Owner

Costs as a Percentage of Household Income in 1989." A separate

question (H23c) determines whether real estate taxes are included in

the mortgage payment to the lender(s). This makes it possible to avoid

counting taxes twice in the computations.

Comparability--Data for real estate taxes were collected for the first time

in 1980. The question was asked only at owner-occupied one-family houses.

Excluded were mobile homes or trailers, condominiums, houses with a

business or medical office on the property, houses on 10 or more acres,

and housing units in multi-unit buildings. In 1990, the question was

asked of all one-family owner-occupied houses, including houses on 10

or more acres. It also was asked at mobile homes, condominiums, and

one-family houses with a business or medical office on the property.

ROOMS

The data on rooms were obtained from questionnaire item H3, which

was asked at both occupied and vacant housing units. The statistics on

rooms are in terms of the number of housing units with a specified

number of rooms. The intent of this question is to count the number of

whole rooms used for living purposes.

For each unit, rooms include living rooms, dining rooms, kitchens,

bedrooms, finished recreation rooms, enclosed porches suitable for

year-round use, and lodger's rooms. Excluded are strip or pullman

kitchens, bathrooms, open porches, balconies, halls or foyers,

half-rooms, utility rooms, unfinished attics or basements, or other

unfinished space used for storage. A partially divided room is a

separate room only if there is a partition from floor to ceiling, but

not if the partition consists solely of shelves or cabinets.

Median Rooms--This measure divides the room distribution into two equal

parts, one-half of the cases falling below the median number of rooms and

one-half above the median. In computing median rooms, the whole number

is used as the midpoint of the interval; thus, the category "3

rooms" is treated as an interval ranging from 2.5 to 3.5 rooms.

Median rooms is rounded to the nearest tenth. (For more information on

medians, see the discussion under "Derived Measures.")

Aggregate Rooms--To calculate aggregate rooms, an arbitrary value of "10"

is assigned to rooms for units falling within the terminal category, "9

or more." (For more information on aggregates and means, see the

discussion under "Derived Measures.")

Comparability--Data on rooms have been collected since 1940. In 1970 and

1980, these data were shown only for year-round housing units. In 1990,

these data are shown for all housing units.

SECOND OR JUNIOR MORTGAGE PAYMENT

The data on second or junior mortgage payments were obtained from

questionnaire items H24a and H24b, which were asked at owner-occupied

one-family houses, condominiums, and mobile homes. Question H24a asks

whether a second or junior mortgage or a home equity loan exists on the

property. Question H24b provides the regular monthly amount required to

be paid to the lender on all second or junior mortgages and home equity

loans. Amounts are included even if the payments are delinquent or paid

by someone else. The amounts reported are included in the computation

of "Selected Monthly Owner Costs" and "Selected Monthly Owner

Costs as a Percentage of Household Income in 1989" for units with a

mortgage.

All mortgages other than first mortgages are classified as

"junior" mortgages. A second mortgage is a junior mortgage that

gives the lender a claim against the property that is second to the

claim of the holder of the first mortgage. Any other junior mortgage(s)

would be subordinate to the second mortgage. A home equity loan is a

line of credit available to the borrower that is secured by real

estate. It may be placed on a property that already has a first or

second mortgage, or it may be placed on a property that is owned free

and clear.

If the respondents answered that no first mortgage existed, but a

second mortgage did (as in the above case with a home equity loan), a

computer edit assigned the unit a first mortgage and made the first

mortgage monthly payment the amount reported in the second mortgage.

The second mortgage data were then made "No" in question H24a and

blank in question H24b.

Comparability--The 1980 census obtained total regular monthly mortgage

payments, including payments on second or junior mortgages, from one single

question. Two questions were used in 1990: one for regular monthly

payments on first mortgages, and one for regular monthly payments on

second or junior mortgages and home equity loans.

SELECTED MONTHLY OWNER COSTS

The data on selected monthly owner costs were obtained from

questionnaire items H20 through H26 for a sample of owner-occupied

one-family houses, condominiums, and mobile homes. Selected monthly

owner costs is the sum of payments for mortgages, deeds of trust,

contracts to purchase, or similar debts on the property (including

payments for the first mortgage, second or junior mortgages, and home

equity loans); real estate taxes; fire, hazard, and flood insurance on

the property; utilities (electricity, gas, and water); and fuels (oil,

coal, kerosene, wood, etc.). It also includes, where appropriate, the

monthly condominium fee for condominiums and mobile home costs

(personal property taxes, site rent, registration fees, and license

fees) for mobile homes.

In certain tabulations, selected monthly owner costs are presented

separately for specified owner-occupied housing units (owner-occupied

one-family houses on fewer than 10 acres without a business or medical

office on the property), owner-occupied condominiums, and

owner-occupied mobile homes. Data usually are shown separately for

units "with a mortgage" and for units "not mortgaged."

Median Selected Monthly Owner Costs--This measure is rounded to the nearest

whole dollar.

Comparability--The components of selected monthly owner costs were

collected for the first time in 1980. The 1990 tabulations of selected

monthly owner costs for specified owner-occupied housing units are

virtually identical to 1980, the primary difference was the amounts of the

first and second mortgages were collected in separate questions in 1990,

while the amounts were collected in a single question in 1980. The

component parts of the item were tabulated for mobile homes and

condominiums for the first time in 1990.

In 1980, costs for electricity and gas were collected as average

monthly costs. In 1990, all utility and fuel costs were collected as

yearly costs and divided by 12 to provide an average monthly cost.

SELECTED MONTHLY OWNER COSTS AS A PERCENTAGE OF HOUSEHOLD INCOME IN

1989

The information on selected monthly owner costs as a percentage of

household income in 1989 is the computed ratio of selected monthly

owner costs to monthly household income in 1989. The ratio was computed

separately for each unit and rounded to the nearest whole percentage.

The data are tabulated separately for specified owner-

occupied units, condominiums, and mobile homes.

Separate distributions are often shown for units "with a mortgage" and for

units "not mortgaged." Units occupied by households reporting no income or

a net loss in 1989 are included in the "not computed" category. (For more

information, see the discussion under "Selected Monthly Owner Costs.")

Comparability--The components of selected monthly owner costs were

collected for the first time in 1980. The tabulations of "Selected Monthly

Owner Costs as a Percentage of Household Income in 1989" for specified

owner-occupied housing units are comparable to 1980.

SEWAGE DISPOSAL

The data on sewage disposal were obtained from questionnaire item H16,

which was asked at both occupied and vacant housing units. This item

was asked on a sample basis. Housing units are either connected to a

public sewer, to a septic tank or cesspool, or they dispose of sewage

by other means. A public sewer may be operated by a government body or

by a private organization. A housing unit is considered to be connected

to a septic tank or cesspool when the unit is provided with an

underground pit or tank for sewage disposal. The category, "Other

means" includes housing units which dispose of sewage in some other

way.

Comparability--Data on sewage disposal have been collected since 1940. In

1970 and 1980, data were shown only for year-round housing units. In 1990,

data are shown for all housing units.

SOURCE OF WATER

The data on source of water were obtained from questionnaire item

H15, which was asked at both occupied and vacant housing units. Housing

units may receive their water supply from a number of sources. A common

source supplying water to five or more units is classified as a

"Public system or private company." The water may be supplied by

a city, county, water district, water company, etc., or it may be

obtained from a well which supplies water to five or more housing

units. If the water is supplied from a well serving four or fewer

housing units, the units are classified as having water supplied by

either an "Individual drilled well" or an "Individual dug

well." Drilled wells or small diameter wells are usually less than

1-1/2 feet in diameter. Dug wells are usually larger than 1-1/2 feet

wide and generally hand dug. The category, "Some other source"

includes water obtained from springs, creeks, rivers, lakes, cisterns,

etc.

Comparability--Data on source of water have been collected since 1940. In

1970 and 1980, data were shown only for year-round housing units. In 1990,

data are shown for all housing units.

TELEPHONE IN HOUSING UNIT

The data on telephones were obtained from questionnaire item H12,

which was asked at occupied housing units. This item was asked on a

sample basis. A telephone must be inside the house or apartment for the

unit to be classified as having a telephone. Units where the respondent

uses a telephone located inside the building but not in the

respondent's living quarters are classified as having no telephone.

Comparability--Data on telephones in 1980 are comparable to 1990. The 1960

and 1970 censuses collected data on telephone availability. A unit was

classified as having a telephone available if there was a telephone

number on which occupants of the unit could be reached. The telephone

could have been in another unit, in a common hall, or outside the

building.

TENURE

The data for tenure were obtained from questionnaire item H4, which

was asked at all occupied housing units. All occupied housing units are

classified as either owner occupied or renter occupied.

Owner Occupied--A housing unit is owner occupied if the owner or co-owner

lives in the unit even if it is mortgaged or not fully paid for. The owner

or co-owner must live in the unit and usually is the person listed in

column 1 of the questionnaire. The unit is "Owned by you or someone

in this household with a mortgage or loan" if it is being purchased

with a mortgage or some other debt arrangement such as a deed of trust,

trust deed, contract to purchase, land contract, or purchase agreement.

The unit is also considered owned with a mortgage if it is built on

leased land and there is a mortgage on the unit.

A housing unit is "Owned by you or someone in this household free

and clear (without a mortgage)" if there is no mortgage or other

similar debt on the house, apartment, or mobile home including units

built on leased land if the unit is owned outright without a mortgage.

Although owner-occupied units are divided between mortgaged and owned free

and clear on the questionnaire, census data products containing 100-percent

data show only total owner-occupied counts. More extensive mortgage

information was collected on the long-form questionnaire and are shown

in census products containing sample data. (For more information, see

the discussion under "Mortgage Status.")

Renter Occupied--All occupied housing units which are not owner occupied,

whether they are rented for cash rent or occupied without payment of cash

rent, are classified as renter occupied. "No cash rent" units are

separately identified in the rent tabulations. Such units are generally

provided free by friends or relatives or in exchange for services such

as resident manager, caretaker, minister, or tenant farmer. Housing

units on military bases also are classified in the "No cash rent"

category. "Rented for cash rent" includes units in continuing

care, sometimes called life care arrangements. These arrangements

usually involve a contract between one or more individuals and a health

services provider guaranteeing the individual shelter, usually a house

or apartment, and services, such as meals or transportation to shopping

or recreation.

Comparability--Data on tenure have been collected since 1890. In 1970, the

question on tenure also included a category for condominium and cooperative

ownership. In 1980, condominium units and cooperatives were dropped

from the tenure item, and since 1980, only condominium units are

identified in a separate question.

For 1990, the response categories were expanded to allow the respondent

to report whether the unit was owned with a mortgage or free and clear

(without a mortgage). The distinction between units owned with a

mortgage and units owned free and clear was added in 1990 to improve

the count of owner-occupied units. Research after the 1980 census

indicated some respondents did not consider their units owned if they

had a mortgage.

UNITS IN STRUCTURE

The data on units in structure (also referred to as "type of

structure") were obtained from questionnaire item H2, which was

asked at all housing units. A structure is a separate building that

either has open spaces on all sides or is separated from other

structures by dividing walls that extend from ground to roof. In

determining the number of units in a structure, all housing units, both

occupied and vacant, are counted. Stores and office space are excluded.

The statistics are presented for the number of housing units in

structures of specified type and size, not for the number of

residential buildings.

1-Unit, Detached--This is a 1-unit structure detached from any other house;

that is, with open space on all four sides. Such structures are considered

detached even if they have an adjoining shed or garage. A one-family house

that contains a business is considered detached as long as the building has

open space on all four sides. Mobile homes or trailers to which one or

more permanent rooms have been added or built also are included.

1-Unit, Attached--This is a 1-unit structure that has one or more walls

extending from ground to roof separating it from adjoining structures. In

row houses (sometimes called townhouses), double houses, or houses attached

to nonresidential structures, each house is a separate, attached structure

if the dividing or common wall goes from ground to roof.

2 or More Units--These are units in structures containing 2 or more housing

units, further categorized as units in structures with 2, 3 or 4, 5 to 9,

10 to 19, 20 to 49, and 50 or more units.

Mobile Home or Trailer--Both occupied and vacant mobile homes to which no

permanent rooms have been added are counted in this category. Mobile homes

or trailers used only for business purposes or for extra sleeping space and

mobile homes or trailers for sale on a dealer's lot, at the factory, or in

storage are not counted in the housing inventory.

Other--This category is for any living quarters occupied as a housing unit

that does not fit the previous categories. Examples that fit this

category are houseboats, railroad cars, campers, and vans.

Comparability--Data on units in structure have been collected since 1940

and on mobile homes and trailers since 1950. In 1970 and 1980, these data

were shown only for year-round housing units. In 1990, these data are shown

for all housing units. In 1980, the data were collected on a sample basis.

The category, "Boat, tent, van, etc." was replaced in 1990 by the

category "Other." In some areas, the proportion of units

classified as "Other" is far larger than the number of units that

were classified as "Boat, tent, van, etc." in 1980.

USUAL HOME ELSEWHERE

The data for usual home elsewhere are obtained from questionnaire

item B, which was completed by census employees. A housing unit

temporarily occupied at the time of enumeration entirely by persons

with a usual residence elsewhere is classified as vacant. The occupants

are classified as having a "Usual home elsewhere" and are counted

at the address of their usual place of residence. Typical examples are

people in a vacation home, persons renting living quarters temporarily

for work, and migrant workers.

Limitation of the Data--Evidence from previous censuses suggests that in

some areas enumerators marked units as "vacant--usual home elsewhere" when

they should have marked "vacant--regular."

Comparability--Data for usual home elsewhere was tabulated for the first

time in 1980.

UTILITIES

The data on utility costs were obtained from questionnaire items

H20a through H20d, which were asked of occupied housing units. These

items were asked on a sample basis.

Questions H20a through H20d asked for the yearly cost of utilities

(electricity, gas, water) and other fuels (oil, coal, wood, kerosene,

etc.). For the tabulations, these yearly amounts are divided by 12 to

derive the average monthly cost and are then included in the

computation of "Gross Rent," "Gross Rent as a Percentage of

Household Income in 1989," "Selected Monthly Owner Costs," and

"Selected Monthly Owner Costs as a Percentage of Household Income in

1989."

Costs are recorded if paid by or billed to occupants, a welfare agency,

relatives, or friends. Costs that are paid by landlords, included in

the rent payment, or included in condominium or cooperative fees are

excluded.

Limitation of the Data--Research has shown that respondents tended to

overstate their expenses for electricity and gas when compared to utility

company records. There is some evidence that this overstatement is reduced

when yearly costs are asked rather than monthly costs. Caution should be

exercised in using these data for direct analysis because costs are not

reported for certain kinds of units such as renter-occupied units with all

utilities included in the rent and owner-occupied condominium units with

utilities included in the condominium fee.

Comparability--The data on utility costs have been collected since 1980 for

owner-occupied housing units, and since 1940 for renter-occupied

housing units. In 1980, costs for electricity and gas were collected as

average monthly costs. In 1990, all utility and fuel costs were

collected as yearly costs and divided by 12 to provide an average

monthly cost.

VACANCY STATUS

The data on vacancy status were obtained from questionnaire item C1,

which was completed by census enumerators. Vacancy status and other

characteristics of vacant units were determined by enumerators

obtaining information from landlords, owners, neighbors, rental agents,

and others. Vacant units are subdivided according to their housing

market classification as follows:

For Rent--These are vacant units offered "for rent," and vacant units

offered either "for rent" or "for sale."

For Sale Only--These are vacant units being offered "for sale only,"

including units in cooperatives and condominium projects if the individual

units are offered "for sale only."

Rented or Sold, Not Occupied--If any money rent has been paid or agreed

upon but the new renter has not moved in as of the date of enumeration, or

if the unit has recently been sold but the new owner has not yet moved in,

the vacant unit is classified as "rented or sold, not occupied."

For Seasonal, Recreational, or Occasional Use--These are vacant units used

or intended for use only in certain seasons or for weekend or other

occasional use throughout the year.

Seasonal units include those used for summer or winter sports or

recreation, such as beach cottages and hunting cabins. Seasonal units

also may include quarters for such workers as herders and loggers.

Interval ownership units, sometimes called shared-ownership or

time-sharing condominiums, also are included here.

For Migrant Workers--These include vacant units intended for occupancy by

migratory workers employed in farm work during the crop season. (Work in a

cannery, a freezer plant, or a food-processing plant is not farm work.)

Other Vacant--If a vacant unit does not fall into any of the

classifications specified above, it is classified as "other vacant." For

example, this category includes units held for occupancy by a caretaker or

janitor, and units held for personal reasons of the owner.

Homeowner Vacancy Rate--This is the percentage relationship between the

number of vacant units for sale and the total homeowner inventory. It is

computed by dividing the number of vacant units for sale only by the sum of

the owner-occupied units and the number of vacant units that are for sale

only.

Rental Vacancy Rate--This is the percentage relationship of the number of

vacant units for rent to the total rental inventory. It is computed by

dividing the number of vacant units for rent by the sum of the renter-

occupied units and the number of vacant units for rent.

Comparability--Data on vacancy status have been collected since 1940. For

1990, the category, "seasonal/recreational/occasional use" combined vacant

units classified in 1980 as "seasonal or migratory" and "held

for occasional use." Also, in 1970 and 1980, housing characteristics

generally were presented only for year-round units. In 1990, housing

characteristics are shown for all housing units.

VALUE

The data on value (also referred to as "price asked" for vacant units) were

obtained from questionnaire item H6, which was asked at housing units that

were owned, being bought, or vacant for sale at the time of enumeration.

Value is the respondent's estimate of how much the property (house and lot,

mobile home and lot, or condominium unit) would sell for if it were for

sale. If the house or mobile home was owned or being bought, but the land

on which it sits was not, the respondent was asked to estimate the combined

value of the house or mobile home and the land. For vacant units, value was

the price asked for the property.

Value was tabulated separately for all owner-occupied and

vacant-for-sale housing units, owner-occupied and vacant-for-sale

mobile homes or trailers, and specified owner-occupied and specified

vacant-for-sale housing units. Specified owner-occupied and specified

vacant-for-sale housing units include only one-family houses on fewer

than 10 acres without a business or medical office on the property. The

data for "specified units" exclude mobile homes, houses with a

business or medical office, houses on 10 or more acres, and housing

units in multi-unit buildings.

Median and Quartile Value--The median divides the value distribution into

two equal parts. Quartiles divide the value distribution into four equal

parts. These measures are rounded to the nearest hundred dollars. (For more

information on medians and quartiles, see the discussion under

"Derived Measures.")

Aggregate Value--To calculate aggregate value, the amount assigned for the

category "Less than $10,000" is $9,000. The amount assigned to the

category "$500,000 or more" is $600,000. Mean value is rounded to

the nearest hundred dollars. (For more information on aggregates and

means, see the discussion under "Derived Measures.")

Comparability--In 1980, value was asked only at owner-occupied or vacant-

for-sale one-family houses on fewer than 10 acres with no business or

medical office on the property and at all owner-occupied or vacant-for-sale

condominium housing units. Mobile homes were excluded. Value data were

presented for specified owner-occupied housing units, specified vacant-for-

sale-only housing units, and owner-occupied condominium housing units.

In 1990, the question was asked at all owner-occupied or

vacant-for-sale-only housing units with no exclusions. Data presented

for specified owner-occupied and specified vacant-for-sale-only housing

units will include one-family condominium houses but not condominiums in

multi-unit structures since condominium units are now identified only in

long-form questionnaires.

For 1990, quartiles have been added because the range of values and

rents in the United States has increased in recent years. Upper and

lower quartiles can be used to note large value and rent differences

among various geographic areas.

VEHICLES AVAILABLE

The data on vehicles available were obtained from questionnaire item

H13, which was asked at occupied housing units. This item was asked on

a sample basis. These data show the number of households with a

specified number of passenger cars, vans, and pickup or panel trucks of

one-ton capacity or less kept at home and available for the use of

household members. Vehicles rented or leased for one month or more,

company vehicles, and police and government vehicles are included if

kept at home and used for nonbusiness purposes. Dismantled or immobile

vehicles are excluded. Vehicles kept at home but used only for business

purposes also are excluded.

Vehicles Per Household--This is computed by dividing aggregate vehicles

available by the number of occupied housing units.

Limitation of the Data--The 1980 census evaluations showed that the number

of automobiles was slightly overreported; the number of vans and trucks

slightly underreported. The statistics do not measure the number of

vehicles privately owned or the number of households owning vehicles.

Comparability--Data on automobiles available were collected from 1960 to

1980. In 1980, a separate question also was asked on the number of trucks

and vans. The data on automobiles and trucks and vans were presented

separately and also as a combined vehicles available tabulation. The

1990 data are comparable to the 1980 vehicles available tabulations.

YEAR HOUSEHOLDER MOVED INTO UNIT

The data on year householder moved into unit were obtained from

questionnaire item H8, which was asked at occupied housing units. This

item was asked on a sample basis. These data refer to the year of the

latest move by the householder. If a householder moved back into a

housing unit he or she previously occupied, the year of the latest move

was reported. If the householder moved from one apartment to another

within the same building, the year the householder moved into the

present apartment was reported. The intent is to establish the year the

present occupancy by the householder began. The year that the

householder moved in is not necessarily the same year other members of

the household moved, although in the great majority of cases an entire

household moves at the same time.

Comparability--In 1960 and 1970, this question was asked of every person

and included in population reports. This item in housing tabulations refers

to the year the householder moved in. In 1980 and 1990, the question was

asked only of the householder.

YEAR STRUCTURE BUILT

The data on year structure built were obtained from questionnaire

item H17, which was asked at both occupied and vacant housing units.

This item was asked on a sample basis. Data on year structure built

refer to when the building was first constructed, not when it was

remodeled, added to, or converted. For housing units under construction

that met the housing unit definition--that is, all exterior windows,

doors, and final usable floors were in place--the category "1989 or

March 1990" was used. For a houseboat or a mobile home or trailer,

the manufacturer's model year was assumed to be the year built. The

figures shown in census data products relate to the number of units

built during the specified periods that were still in existence at the

time of enumeration.

Median Year Structure Built--The median divides the distribution into two

equal parts. The median is rounded to the nearest calendar year. Median age

of housing can be obtained by subtracting median year structure built from

1990. For example, if the median year structure built is 1957, the median

age of housing in that area is 33 years (1990 minus 1957).

Limitation of the Data--Data on year structure built are more susceptible

to errors of response and nonreporting than data on many other items

because respondents must rely on their memory or on estimates by persons

who have lived in the neighborhood a long time. Available evidence

indicates there is underreporting in the older-year-structure- built

categories, especially "Built in 1939 or earlier." The introduction of the

"Don't know" category (see the discussion on "Comparability") may have

resulted in relatively higher allocation rates. Data users should refer to

the discussion in Appendix C, Accuracy of the Data, and to the allocation

tables.

Comparability--Data on year structure built were collected for the first

time in the 1940 census. Since then, the response categories have been

modified to accommodate the 10-year period between each census. In 1990,

the category, "Don't Know," was added in an effort to minimize the

response error mentioned in the paragraph above on limitation of the

data.

DERIVED MEASURES

Census data products include various derived measures, such as

medians, means, and percentages, as well as certain rates and ratios.

Derived measures that round to less than 0.1 are not shown but

indicated as zero. In printed reports, zero is indicated by a dash

(-).

Interpolation

Interpolation frequently is used in calculating medians or quartiles

based on interval data and in approximating standard errors from

tables. Linear interpolation is used to estimate values of a function

between two known values. "Pareto interpolation" is an

alternative to linear interpolation. It is used by the Census Bureau in

calculating median income within intervals wider than $2,500. In Pareto

interpolation, the median is derived by interpolating between the

logarithms of the upper and lower income limits of the median category.

Mean

This measure represents an arithmetic average of a set of values. It

is derived by dividing the sum of a group of numerical items (or

aggregate) by the total number of items. Aggregates are used in

computing mean values. For example, mean family income is obtained by

dividing the aggregate of all income reported by persons in families by

the total number of families. (Additional information on means and

aggregates is included in the separate explanations of many population

and housing subjects.)

Median

This measure represents the middle value in a distribution. The

median divides the total frequency into two equal parts: one-half of

the cases fall below the median and one-half of the cases exceed the

median. The median is computed on the basis of the distribution as

tabulated, which is sometimes more detailed than the distribution shown

in specific census publications and other data products.

In reports, if the median falls within the upper interval of the

tabulation distribution, the median is shown as the initial value of

the interval followed by a plus sign (+); if within the lower interval,

the median is shown as the upper value of the category followed by a

minus sign (-). For summary tape files, if the median falls within the

upper or lower interval, it is set to a specified value. (Additional

information on medians is included in the separate explanations of many

population and housing subjects.)

Percentages, Rates, and Ratios

These measures are frequently presented in census products to

compare two numbers or two sets of measurements. These comparisons are

made in two ways: (1) subtraction, which provides an absolute measure

of the difference between two items, and (2) the quotient of two

numbers, which provides a relative measure of difference.

Quartile

This measure divides a distribution into four equal parts. The first

quartile (or lower quartile) is the value that defines the upper limit

of the lowest one-quarter of the cases. The second quartile is the

median. The third quartile (or upper quartile) defines the lower limit

of the upper one-quarter of the cases in the distribution. The

difference between the upper and lower quartiles is called the

interquartile range. This interquartile range is less affected by wide

variations than is the mean. Quartiles are presented for certain

financial characteristics such as housing value and rent.