Technical Documentation

This page contains technical documentation and related information on the Current Population Survey (CPS).

Concepts and methodology of the CPS

Summarized documentation on the concepts and methodology of the CPS.

  • Quick Guide to Methods and Measurement Issues in the monthly Employment Situation report (HTML)
  • Handbook of Methods, chapter 1, labor force data derived from the Current Population Survey
    (HTML) (PDF)
  • Technical notes to household survey data published in Employment and Earnings
    • Introduction (Relationship and comparability with establishment and other surveys) (PDF)
    • Collection and Coverage, Concepts and Definitions, Historical Comparability and Estimating Methods (PDF)
    • Seasonal adjustment (PDF)

Comprehensive documentation on the design and methodology of the CPS, including a history of the survey (links to the Census Bureau website).

  • Current Population Survey, design and methodology (Technical paper 66) (October 2006) (PDF 3.2MB)
    • Previous versions:
      • Technical paper 63, revised March 2002 (PDF 3.1MB)
      • Technical paper 63, March 2000 (PDF 2.2MB)

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.

  • Revisions to the Current Population Survey effective in January 2003 (PDF)

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.

  • Report: Recent trends in employment from the BLS household and payroll surveys (updated monthly) (PDF)
  • Quick Guide to Methods and Measurement Issues in the monthly Employment Situation report (HTML)
  • Article: Understanding the employment measures from the establishment and household surveys (February 2006)
    (Abstract) (Excerpt) (PDF)

How the government measures unemployment

Documentation describing how the national unemployment statistics are developed from the CPS, written in non-technical language.

  • How the government measures unemployment (HTML)

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).

  • Documentation on the 2002 Census occupational and industry classifications, with crosswalks to the SOC and NAICS. (HTML)
  • Information on the availability of selected historical employment data constructed on the 2002 Census occupational and industry classifications (HTML)
  • Documentation of the revisions to the Current Population Survey in January 2003, including the conversion to the 2002 Census classifications (PDF)
  • More information on the Census occupational and industry classifications is available from the Census Bureau.

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 Census Bureau reviews and adjusts the population controls every year. BLS introduces the annual population control adjustments into the CPS estimates beginning with the January data. The adjustment can either increase or decrease the population level, depending on whether the latest information indicates the population estimates have trended too high or low. Conceptually, the population control adjustments represent the cumulative over- or under-estimation of the population since the last decennial census point.

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.

  • Labor force and employment research series, smoothed for population control adjustments made since January 2000 (PDF)
  • Documentation on the methodology used to create the smoothed labor force and employment research series (PDF)

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.

  • Household data, reliability of estimates; see pages 12-19 (printed pages 193-200) (PDF)

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.

  • Seasonal adjustment overview (PDF).
  • Description of recent modifications in the seasonal adjustment of national labor force statistics from the CPS
    PDF 2008 2007 2006 2005 2004


Last Modified Date: June 20, 2008