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APPENDIX B.
Definitions of Subject Characteristics
CONTENTS
POPULATION CHARACTERISTICS B-1
Age B-1
American Indian Tribe (See Race)
Families (See Household Type and Relationship)
Family Composition (See Household Type and Relationship)
Family Size (See Household Type and Relationship)
Family Type (See Household Type and Relationship)
Foster Children (See Household Type and Relationship)
Group Quarters B-2
Hispanic Origin B-7
Household Size (See Household Type and Relationship)
Household Type and Relationship B-8
Householder (See Household Type and Relationship)
Households (See Household Type and Relationship)
Institutionalized Persons (See Group Quarters)
Marital Status B-10
Married Couples (See Marital Status)
Noninstitutional Group Quarters (See Group Quarters)
Own Children (See Household Type and Relationship)
Persons in Family (See Household Type and Relationship)
Persons in Household (See Household Type and Relationship)
Presence of Children (See Household Type and Relationship)
Race B-11
Related Children (See Household Type and Relationship)
Sex B-14
Spanish Origin (See Hispanic Origin)
HOUSING CHARACTERISTICS B-14
Acreage B-15
Boarded-Up Status B-15
Business on Property B-16
Congregate Housing (See Meals Included in Rent)
Contract Rent B-16
Duration of Vacancy B-16
Homeowner Vacancy Rate (See Vacancy Status)
Housing Units (See Living Quarters)
Living Quarters B-14
Meals Included in Rent B-17
Months Vacant (See Duration of Vacancy)
Occupied Housing Units (See Living Quarters)
Owner-Occupied Housing Units (See Tenure)
Persons (See Persons in Unit)
Persons in Unit B-17
Persons Per Room B-17
Rental Vacancy Rate (See Vacancy Status)
Renter-Occupied Housing Units (See Tenure)
Rooms B-17
Tenure B-18
Type of Structure (See Units in Structure)
Units in Structure B-18
Usual Home Elsewhere B-19
Vacancy Status B-19
Vacant Housing Units (See Living Quarters)
Value B-19
DERIVED MEASURES B-20
Interpolation B-20
Mean B-20
Median B-20
Percentages, Rates, and Ratios B-21
Quartile B-21
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 completed years as of April 1, 1990. The age
response in question 5a was normally used 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 in 1990.
Review of detailed 1990 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 completed 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.)
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 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, transient quarters on base for temporary residents
(both civilian and military), and military ships. However, patients in
military hospitals receiving treatment for chronic diseases or who have
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 which 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 census day 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 enumerated with no
usual home elsewhere 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":
1. 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.)
2. 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 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:
1. How well enumerators were trained and how well they followed
procedures.
2. 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.
3. 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.
4. 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.
5. The media occasionally interfered with the ability to do the count.
6. 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 York, New Orleans, 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).
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.
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.
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 table A 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, Philippine, 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 table A 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 race
categories 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 table A 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 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. Since sample processing included additional editing, there may be
some minor differences between sample data and 100-percent data.
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."
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Table A. 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)
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(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.
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 the 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.
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.
HOUSING CHARACTERISTICS
LIVING QUARTERS
Living quarters are classified as either housing units or group
quarters. (For more information, see 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, caves, 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 contain 9 or more persons unrelated to the
householder or person in charge (a total of 10 unrelated persons), they
are classified as group quarters. If the living quarters contain eight
or fewer persons unrelated to the householder or person in charge, they
are classified as housing units.
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. 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.
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 are also 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; for example, 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 item H5a, which
was asked at all occupied and vacant one-family houses and mobile
homes. 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 or creek, or another piece of land. This question is used to
exclude owner-occupied and renter-occupied one-family houses and mobile
homes with 10 or more acres from certain statistics on financial
characteristics.
Comparability--The question on acreage is the same in 1970 and 1980 and was
asked for the first time of mobile home occupants in the 1990 census.
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 and mobile home units with business or medical offices from
certain statistics on financial characteristics.
A business must be easily recognizable from the outside. It will
usually have a separate outside entrance and have the appearance of a
business, such as a grocery store, restaurant, or barbershop. 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.
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 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 on rent, see the discussion under "Gross
Rent" in census products containing sample data.)
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 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. (For more information on
aggregates and means, see the discussion under "Derived Measures.")
Comparability--Data on this item have been collected since 1940. 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 housing units. In 1990,
these 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 is generally considered to be housing
units where the rent includes meals and other services, such as
transportation to shopping and recreation.
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.")
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.
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 housing 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.
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 a 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 or 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
structure, 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 which 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 are also
included.
1-Unit, Attached--This is a 1-unit structure which 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
of 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 were 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 were tabulated for the first
time in 1980.
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 may also include
quarters for such workers as herders and loggers.
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 feed
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
were generally 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 occupied 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 is owned or being bought, but the land on which it sits is
not, the respondent was asked to estimate the combined value of the
house or mobile home and the land. For vacant units, value is the price
asked for the property.
Value is tabulated separately for all owner-occupied and
vacant-for-sale-only housing units, owner-occupied and vacant-for-sale
mobile homes or trailers, and specified owner-occupied and specified
vacant-for-sale-only housing units. Specified owner-occupied and
specified vacant-for-sale-only housing units include only one-
family houses on less 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 whole dollar. (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 less 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.
DERIVED MEASURES
Census data products include various derived measures such as
medians, means, and percentages, as well as certain rates and ratios.
Derived measures which round to less than 0.1 are not shown but
indicated as zero. In printed reports, zero is indicated by showing a
dash (-).
Interpolation
Interpolation is frequently 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 logarithm of 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 an
open-ended distribution, the median is shown as the initial value of
the interval followed by a plus sign (+), or 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 and are used 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.
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