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| The '''American Community Survey''' ('''ACS''') is an annual survey operated by the Census Bureau to establish demographic information about the nation's population. | The '''American Community Survey''' ('''ACS''') is a continual survey operated by the Census Bureau. |
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| === Sampling === The CPS utilizes a multi-level probability sample of about 72,000 housing units. It is designed to reflect the civilian noninstitutionalized U.S. population aged 16 or older. Each state plus [[UnitedStates/WashingtonDC|D.C.]] is an independent sample. NY is subdivided into [[UnitedStates/NewYorkCity|NYC]] and 'balance of NY', and CA is subdivided into [[UnitedStates/LosAngeles|LA county]] and 'balance of CA'; each substate area is an independent sample. |
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| The ACS is administered annually, with continuous data collection. No household is sampled more than once in 5 years. | The survey uses an annual sample, which is counted as beginning in April. No household is sampled more than once in 5 years. |
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| 1-year estimates are usually published in the fall, and 5-year estimates are usually published in the winter. | Each month the survey is administered to panels ('rotation groups'). Each panel is a replicate. Panel members are interviewed for 4 consecutive months, then dropped from the sample for 8 months, then interviewed for 4 more consecutive months. By this design, in any given month, there are 8 panels in sample and 1/8 of the sample is interviewed for the first time. There is 75% overlap month-to-month and a 50% overlap year-to-year. Data is collected into annual vintages; '1-year estimates' are usually published in the Fall. Data is further aggregated into a rolling 5-year window for '5-year estimates'. === Weighting === Units carry a base weight equal to the inverse selection probability. Nonresponse adjustments are calculated with respect to eligible households. That is, vacant or demolished structures that were sampled are not used for this adjustment. A first-stage adjustment factor is calculated to calibrate the 'Black alone'/'non-Black alone' population distribution. Within each state, four adjustment cells are calculated with respect to race (Black alone and non-Black alone) and age (0-15 and 16+). Population controls are taken from the census. The race cells are collapsed if there are fewer than 4 sampled PSUs in the state, or if there are fewer than 10 respondents per month, or if the adjustment factor is outside the range of 0.5 to 1.5. This is done separately for each panel. Panels are then paired according to the number of months spent in sample. This helps to correct for 'months-in-sample' (MIS) bias. MIS 1 is paired with MIS 5, MIS 2 is paired with MIS 6, and so on. These pairs are combined for all subsequent adjustments. The weights are then calibrated to national population controls by age, sex, race, and ethnicity. Sparse cells are collapsed if there are fewer than 20 respondents per month or if the adjustment factor is outside the range of 0.6 to 2.0. The weights are then calibrated to state population controls by race, sex, and age. Sparse cells are collapsed if there are fewer than 20 respondents per month or if the adjustment factor is outside the range of 0.6 to 2.0. A second-stage adjustment factor is a raking procedure over dimensions defined by: * state by sex by age * ethnicity by sex by age * race by sex by age 10 iterations are used to converge onto the population controls. |
American Community Survey
The American Community Survey (ACS) is a continual survey operated by the Census Bureau.
Usage
See here for notes on the public use microdata.
Design
Sampling
The CPS utilizes a multi-level probability sample of about 72,000 housing units. It is designed to reflect the civilian noninstitutionalized U.S. population aged 16 or older.
Each state plus D.C. is an independent sample. NY is subdivided into NYC and 'balance of NY', and CA is subdivided into LA county and 'balance of CA'; each substate area is an independent sample.
Frequency
The survey uses an annual sample, which is counted as beginning in April. No household is sampled more than once in 5 years.
Each month the survey is administered to panels ('rotation groups'). Each panel is a replicate.
Panel members are interviewed for 4 consecutive months, then dropped from the sample for 8 months, then interviewed for 4 more consecutive months. By this design, in any given month, there are 8 panels in sample and 1/8 of the sample is interviewed for the first time. There is 75% overlap month-to-month and a 50% overlap year-to-year.
Data is collected into annual vintages; '1-year estimates' are usually published in the Fall.
Data is further aggregated into a rolling 5-year window for '5-year estimates'.
Weighting
Units carry a base weight equal to the inverse selection probability.
Nonresponse adjustments are calculated with respect to eligible households. That is, vacant or demolished structures that were sampled are not used for this adjustment.
A first-stage adjustment factor is calculated to calibrate the 'Black alone'/'non-Black alone' population distribution. Within each state, four adjustment cells are calculated with respect to race (Black alone and non-Black alone) and age (0-15 and 16+). Population controls are taken from the census. The race cells are collapsed if there are fewer than 4 sampled PSUs in the state, or if there are fewer than 10 respondents per month, or if the adjustment factor is outside the range of 0.5 to 1.5. This is done separately for each panel.
Panels are then paired according to the number of months spent in sample. This helps to correct for 'months-in-sample' (MIS) bias. MIS 1 is paired with MIS 5, MIS 2 is paired with MIS 6, and so on. These pairs are combined for all subsequent adjustments.
The weights are then calibrated to national population controls by age, sex, race, and ethnicity. Sparse cells are collapsed if there are fewer than 20 respondents per month or if the adjustment factor is outside the range of 0.6 to 2.0.
The weights are then calibrated to state population controls by race, sex, and age. Sparse cells are collapsed if there are fewer than 20 respondents per month or if the adjustment factor is outside the range of 0.6 to 2.0.
A second-stage adjustment factor is a raking procedure over dimensions defined by:
- state by sex by age
- ethnicity by sex by age
- race by sex by age
10 iterations are used to converge onto the population controls.
Geographies
1-year estimates are published for geographic areas with populations of 65,000 or more. This threshold is set so that estimates can be made available for all states, territories, congressional districts, PUMAs, CBSAs, cities, and Native American areas.
5-year estimates are published for geographic areas with much smaller population levels. This includes ZCTAs, census tracts, and census block groups.
History
The ACS was launched in 2005 as a replacement for the long-form U.S. census. It provides more timely data because data collection is continuous, and then published in a periodic aggregation. It is used to allocate federal and state funding.