Sample characteristics: United States

Census characteristics

1960

1970

1980

1990

2000

Title

1960 Census of Population and Housing

1970 Census of Population and Housing

1980 Census of Population and Housing

1990 Census of Population and Housing

2000 Census of Population and Housing

Census agency

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

Population
universe

Residents of the 50 states (not the outlying
areas).

Residents of the 50 states (not the outlying
areas).

Residents of the 50 states (not the outlying
areas).

Residents of the 50 states (not the outlying
areas).

Residents of the 50 states (not the outlying
areas).

De jure or de
facto

De jure

De jure

De jure

De jure

De jure

Enumeration unit

Households and Group Quarters

Households and Group Quarters

Households and Group Quarters

Households and Group Quarters

Households and Group Quarters

Census day

April 1, 1960

April 1, 1970

April 1, 1980

April 1, 1990

April 1, 2000

Enumeration forms

The 1960 census used a machine-readable household
form. Separate forms were used for each housing unit. Housing
questions were included on the same form as the population items.
Every fourth enumeration unit received a "long form," containing
supplemental sample questions that were asked of all members of the
unit. Sample questions are available for all individuals in every
unit. Of the units receiving a long form, four-fifths received one
version (the 20% questionnaire), and one-fifth received a second
version with the same population questions but slightly different
housing questions (the 5% questionnaire).

One in five housing units in 1970 received a long
form containing supplemental sample questions. There were two
versions of the long form, with different inquiries on both housing
and population items; 15 percent of households received one version,
and 5 percent received the other. Six independent 1 percent public
use samples were produced for 1970, three from the 15 percent
questionnaire and three from the 5 percent questionnaire.

The 1980 census employed a single long form
questionnaire completed by one-half of housing units in places with
a population under 2,500 and one-sixth of other housing units.

The 1990 census used a single long-form questionnaire
completed by one-half of persons in places with a population under
2,500, one-sixth of persons in other tracts and block numbering
areas with fewer than 2,000 housing units, and one-eighth of all
other areas. Overall, about one-sixth of housing units completed a
long form.

The 2000 census used a long form questionnaire. Long
Form Sampling Entities (LFSEs) were used to determine sampling
rates. If the smallest LFSE that included all or any part of a block
had an estimated housing unit count of less than 800, the housing
units in the block were sampled at a 1-in-2 rate. If it had an
estimated housing unit count of 800 or more but less than 1,200,
units were sampled at a 1-in-4 rate. If a block was not in either of
the two previous categories, and was part of an interim census tract
with 2,000 or more estimated housing units, units were sampled at a
1-in-8 rate. Housing units in all remaining blocks were sampled at a
1-in-6 rate. When all sampling rates were taken into account across
the nation, approximately 1 out of every 6 housing units was
included in the Census 2000 sample.

Type of fieldwork

Direct and self-enumeration

Direct and self-enumeration

Direct and self-enumeration

Direct and self-enumeration

Direct and self-enumeration

Respondent

Household

Not specified

Not specified

Not specified

Not specified

Undercount

No official estimates

No official estimates

No official estimates

No official estimates

No official estimates

Microdata sample characteristics

1960

1970

1980

1990

2000

Microdata source

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

U.S. Census Bureau

Sample unit

Household

Household

Household

Household

Household

Sample fraction

1%

1%

5%

5%

5%

Sample size (person
records)

1,799,888

2,029,666

11,343,120

12,501,046

14,081,466

Sample weights

Self-weighting.

Expansion factor = 100.

Self-weighting.

Expansion factor = 100.

Self-weighting.

Expansion factor = 100.

Weights computed by census agency should be used for
most types of analysis.

Weights computed by census agency should be used for
most types of analysis.

Units identified

1960

1970

1980

1990

2000

Dwellings

No

No

No

No

No

Vacant units

No

Yes

Yes

Yes

Yes

Unit definitions

1960

1970

1980

1990

2000

Households

Not available in microdata sample

Yes

Yes

Yes

Yes

Individuals

Yes

Yes

Yes

Yes

Yes

Group quarters

Yes

Yes

Yes

Yes

Yes

Households

Dwelling places with fewer than five persons
unrelated to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than five persons
unrelated to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than ten persons unrelated
to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than ten persons unrelated
to a household head, excluding institutions and transient
quarters.

Dwelling places excluding institutions and transient
quarters.

Group quarters

Dwelling places with fewer than five persons
unrelated to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than five persons
unrelated to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than ten persons unrelated
to a household head, excluding institutions and transient
quarters.

Dwelling places with fewer than ten persons unrelated
to a household head, excluding institutions and transient
quarters.

No threshold was applied; in order for a household to
be considered group quarters in 2000, it had to be on the list of
group quarters that is continuously maintained by the Census
Bureau.

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