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.

  • How the government measures unemployment (HTML) (PDF)
  • Understanding BLS Unemployment Statistics (Video)
  • 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 (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 U.S. 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)
  • Newly available online: Documentary video on the development of the Current Population Survey
    Produced circa 1990 to commemorate the 50th anniversary of the survey

  • Additional information about the CPS, including documentation for survey microdata, is available from the Census Bureau

Historical comparability is affected by revisions to population controls, changes in occupational and industry classification, and other changes to the survey.

  • History of the Current Population Survey in Chapter 2 (pages 13-19) of Technical Paper 66
  • Discussion of historical comparability; see pages 3-11 (printed pages 184-192) (PDF)
  • Addition of survey questions on professional certification and licenses in 2015
  • Redesign of the Sample for the Current Population Survey, April 2014 (PDF)
  • Changes to data collected on unemployment duration introduced in 2011
  • Addition of survey questions to identify people with a disability in 2008
  • Redesign of the Sample for the Current Population Survey, from Employment and Earnings, December 2004 (PDF)
  • Revisions to the Current Population Survey Effective in January 2003, including new questions on race and Hispanic ethnicity, updated population controls, and new occupational and industry classifications (PDF)
  • Expansion of the Current Population Survey Sample Effective July 2001, from Employment and Earnings, August 2001 (PDF)
  • CPS redesign implemented in January 1994, including questionnaire changes and updated population controls.

CPS and CES employment differences

BLS has two monthly surveys that measure employment levels and trends:

  • the Current Population Survey (CPS), also known as the household survey
  • the Current Employment Statistics (CES) survey, also known as the payroll or establishment survey

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.

Chart: Household and payroll survey employment, seasonally adjusted, 1994 to present (updated monthly)

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.

  • How the government measures unemployment (HTML) (PDF)
  • Understanding BLS Unemployment Statistics (Video)

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 personís sole or primary job, unless otherwise specified. For the unemployed, the occupation and industry are based on the last job held.

The Current Population Survey currently uses the 2010 Census occupational classification and the 2012 Census industry classification. These classifications were derived from the 2010 Standard Occupational Classification (SOC) and the 2012 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.

  • 2010 Census Occupation Titles and Code List (PDF) (XLSX) (HTML)
    • Includes a crosswalk to the 2010 SOC
  • 2012 Census Industry Titles and Code List (PDF) (XLSX) (HTML)
    • Includes a crosswalk to the 2012 NAICS

More information about the Census occupational and industry classifications is available from the Census Bureau, including indexes showing where specific jobs and industries are classified.

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 in January 2018 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

  • Article: Revisions to the Current Population Survey effective in January 2003 (PDF)
  • Discussion of historical comparability, including adjustments to the population controls over time (PDF, page 5)

Labor force and employment research series smoothed for population control adjustments

Level shifts in the CPS labor force and employment series may result from the annual population control adjustments. Significant level shifts may make it difficult for data users to evaluate changes over time periods that include these adjustments. As a convenience to data users, BLS created research series that smooth out level shifts in the labor force and employment estimates resulting from the January 2000 and subsequent population control adjustments.

The smoothed research series end with December of the prior calendar year and are meant to be used with current-year data from the official labor force and employment series.

  • Description of the labor force and employment research series smoothed for population control adjustments (PDF)
    • Table: Labor force research series smoothed for population control adjustments, seasonally adjusted (XLSX)
    • Table: Employment research series smoothed for population control adjustments, seasonally adjusted (XLSX)
  • Documentation on the methodology used to create the smoothed labor force and employment research series (PDF)

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.

  • Table: Changes in selected labor force indicators with a statistical significance test (updated monthly) (PDF) (HTML)
  • Calculating approximate standard errors and confidence intervals for CPS estimates (PDF)
    • Parameters and factors for calculating standard errors, tables PF-1 through PF-16 (XLSX)

Research articles

Browse recent BLS analyses of CPS data by topic: unemployment, labor force characteristics, earnings, and demographic characteristics.

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, Methodology for Seasonally Adjusting National Household Survey Labor Force Series.

Archived seasonal adjustment methodology articles

2017 2016 2015 2014 2013 2012 2011
2010 2009 2008 2007 2006 2005 2004
2003 2002 1999 1998 1990

Research articles on CPS seasonal adjustment

  • Seasonal Adjustment of CPS Labor Force Series During the Great Recession (October 2013) (Abstract) (PDF)
  • Model-based seasonally adjusted estimates and sampling error (September 2005) (PDF)
  • An Evaluation of Concurrent Seasonal Adjustment for the Major Labor Force Series (August 1987) (PDF)


Last Modified Date: February 2, 2018