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 Census Bureau website).
Documentation on changes implemented in the CPS in January 2003, including new questions on race and Hispanic ethnicity, updated population controls, and new occupational and industry classifications.
Expansion of the Current Population Survey Sample Effective July 2001, from Employment and Earnings, August 2001 (PDF)
CPS and CES employment differences
There are two monthly surveys that provide sample-based estimates of employment: the CPS, also known as the household survey, and the Current Employment Statistics (CES) survey, also known as the establishment or payroll survey. The establishment survey employment series has a smaller margin of error on the measurement of month-to-month change than the household survey because of its much larger sample size. However, the household survey has a more expansive scope than the establishment survey because it includes the self-employed, unpaid family workers, agricultural workers, and private household workers, who are excluded by the establishment survey. The household survey also provides estimates of employment for demographic groups.
How the government measures unemployment
Documentation describing how the national unemployment statistics are developed from the CPS, written in non-technical language.
Occupational and industry classification used in the CPS
The Current Population Survey currently uses the 2002 Census occupational and industry classifications. These classifications were derived from the 2000 Standard Occupational Classification (SOC) and the 2002 North American Industry Classification System (NAICS).
Population control adjustments to the CPS
The CPS population controls are the weights used to adjust the survey sample results to reflect the civilian noninstitutional population 16 and older. The population controls are developed by the U.S. Census Bureau. They are based on decennial census information, and between decennial census years they incorporate administrative data, such as birth and death statistics, along with the Census Bureau's estimates of net international migration (reflecting both legal and illegal immigration).
The level shifts in the CPS labor force and employment series resulting from annual population adjustments can make it difficult for data users to compare changes over time periods that include these adjustments. As a convenience to its data users, BLS created research series that smooth out the level shifts in the labor force and employment estimates resulting from the January 2000 and subsequent population control adjustments.
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.
Seasonal adjustment of CPS estimates
Over the course of a year, the size of the labor force, the levels of employment and unemployment, and other measures of labor market activity undergo sharp fluctuations due to such seasonal events as changes in weather, major holidays, and the opening and closing of schools. Because these seasonal events follow a more or less regular pattern each year, their influence on statistical trends can be eliminated by adjusting the statistics from month to month. These adjustments make it easier to observe the cyclical and other nonseasonal movements in the series. BLS regularly produces seasonally adjusted series for selected labor force data from the CPS.
Last Modified Date: June 20, 2008
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