Current Population Survey
The Current Population Survey (CPS), sometimes known as the household survey, is a continual survey operated by the Census Bureau and BLS.
Usage
See here for notes on the public use microdata.
Design
Sampling
The survey 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.
No household is sampled more than once in 5 years.
Frequency
The survey uses an annual sample, which is counted as beginning in April.
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.
Mode
The survey is administered as a phone survey. For the first month, most respondents are visited in-person.
Frequency
The questionnaire inquires about the prior week.
Households are contacted for four consecutive months. After eight months of non-contact, they are again contacted for another four consecutive months.
Updated estimates are published on the first Friday of every month. (If this falls on a public holiday, the release is pushed to Thursday.) The public use microdata is published as the 'Basic Monthly CPS' as is available from services including MDAT. The Current Employment Statistics (CES) program which encompasses this 'household survey' alongside the payroll survey, publishes a monthly 'Employment Situation' report.
Supplemental surveys that cover additional topics are included in the CPS administration. For example, the Annual Social and Economic (ASEC) supplement is included every year in March and published in the Fall. Some supplements have been included on an ad hoc basis.
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.
History
The CPS began in 1940. In 1942, the Census Bureau was made responsible for its administration.