- Concepts and methodology
- CPS and CES employment differences
- Historical comparability
- How the government measures unemployment
- Occupational and industry classification
- Population control adjustments
This page contains technical documentation and related information on the Current Population Survey (CPS).
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Concepts and methodology of the CPS
Summarized documentation on the concepts and methodology of the CPS.
Comprehensive documentation on the design and methodology of the CPS, including a history of the survey (links to the U.S. Census Bureau website).
CPS and CES employment differences
BLS has two monthly surveys that measure employment levels and trends:
See Comparing employment from the BLS household and payroll surveys for information on the differences in the two employment measures, as well as trend divergences that sometimes occur.
How the government measures unemployment
Description of how the national unemployment statistics are developed from the Current Population Survey (CPS), written in non-technical language.
Occupational and industry classifications used in the CPS
BLS publishes both employment and unemployment data by occupation and industry from the CPS.
The occupational classification reflects the type of job or work that the person does, while the industry classification reflects the business activity of their employer or company. The occupational and industry classifications are based on a person's sole or primary job, unless otherwise specified. For the unemployed, the occupation and industry are based on the last job held.
Beginning with data for January 2020, the Current Population Survey uses the 2018 Census occupational classification and the 2017 Census industry classification. These classifications were derived from the 2018 Standard Occupational Classification (SOC) and the 2017 North American Industry Classification System (NAICS), respectively, to meet the special classification needs of demographic household surveys. The Census classifications use the same basic structure as the SOC and NAICS, but are generally less detailed.
Learn more about the historical comparability of occupation and industry data from the CPS.
Population control adjustments to the CPS
Population controls are independent estimates of population used to weight the CPS sample results to reflect the civilian noninstitutional population age 16 and older.
The U.S. Census Bureau develops the CPS population controls. They are based on the latest decennial census population count, supplemented with birth and death data and estimates of net international migration. The population estimation methodology is available on the Census Bureau's website.
The Census Bureau adjusts the CPS population controls each year to include the latest information about population change and to incorporate any improvements in the estimation methodology. Following a decennial census, a new population base is introduced along with the adjustments.
BLS incorporates the annual population control adjustments into the CPS estimates with data for January.
The adjustments may increase or decrease the population level, depending on whether the latest information indicates the population estimates had trended high or low. Conceptually, the effects of the annual population control adjustments represent cumulative over- or under-estimation of the population since the last decennial census point.
See Adjustments to Household Survey Population Estimates for a description of the latest population control adjustments to the CPS, and a supplemental table with the latest adjustment effects.
Archived information on the annual population control adjustments
Additional information related to CPS population controls
Labor force and employment research series smoothed for population control adjustments
Notice to Smoothed Series Data Users
BLS will no longer update the smoothed labor force and employment research series.
These series, which run from January 1990–December 2017, were last updated in February 2018. They will remain available online for interested data users, but no further extensions or revisions to the series are planned.
As a convenience to data users, BLS provided and updated the smoothed labor force and employment research series from 2003–2018. Their purpose was to aid analysis by smoothing out noneconomic level shifts that may occur in the data between December and January when the annual adjustments to survey population controls are introduced. They were developed in 2003 when the introduction of the Census 2000 population base caused substantial level shifts in the labor force and employment series.
Questionnaire for the CPS
Information about the survey collection process, including the questionnaire, is available from the Census Bureau, which conducts the CPS.
Reliability of estimates from the CPS
Statistics from the CPS are subject to both sampling and nonsampling error. When a sample rather than the entire population is surveyed, there is a chance that the sample estimates may differ from the "true" population values they represent. The exact difference, or sampling error, varies depending on the particular sample selected, and this variability is measured by the standard error of the estimate.
Survey methods research:
Seasonal adjustment of CPS estimates
Labor force levels, employment, unemployment, and other labor market measures sharply fluctuate over the course of a year due to seasonal events such as weather, major holidays, and the opening and closing of schools. Seasonal adjustment is a statistical procedure used to remove seasonal fluctuations from data series, making it easier to observe cyclical and other economic trends. BLS produces a wide range of seasonally adjusted labor market measures from the CPS.
Current procedures for seasonally adjusting CPS data are described in the article Seasonal Adjustment Methodology for National Labor Force Statistics from the Current Population Survey.
At the end of each calendar year, the Bureau of Labor Statistics (BLS) reestimates the seasonal factors for the CPS series by including another full year of data in the estimation process. Following this annual reestimation, BLS revises the historical seasonally adjusted data for the previous 5 years.
The most recent revisions to seasonally adjusted CPS series are described in Revisions to seasonally adjusted national household survey labor force series.
Archived articles describing CPS seasonal adjustment methodology and annual updates to the seasonally adjusted series
Research articles on CPS seasonal adjustment
Last Modified Date: June 16, 2022