U.S. Bureau of Labor Statistics 

Current Population Survey (CPS) 

Technical Documentation 

January 2020 

 

Documentation for prior years is available at 

www.bls.gov/cps/documentation.htm#saarchive 

Revisions to seasonally adjusted national household survey 

labor force series effective in January 2020 

At the end of each calendar year, the Bureau of Labor Statistics (BLS) reestimates the seasonal 

factors for the Current Population Survey (CPS, or household survey) series by including another 

full year of data in the estimation process. 

Following this annual reestimation, BLS seasonally adjusted national household survey labor force 

data for the previous 5 years are subject to revision. The revised historical data are released in 

January each year with the publication of the latest December data. 

As a result, each year’s data are generally subject to five revisions before the values are considered 

final. The fifth and final revisions to data for the earliest of the 5 years are usually quite small, while 

the first-time revisions to data for the most recent years are generally much larger. For the major 

aggregate labor force series, however, the first-time revisions rarely alter the essential trends 

observed in the initial estimates. For detailed information about the seasonal adjustment procedures, 

see www.bls.gov/cps/seasonal-adjustment-methodology.htm. 

Revisions to 2019 estimates 

This year’s revisions incorporate data through December 2019 and provide revised estimates for 

January 2015 through November 2019 for all previous seasonally adjusted labor force series. 

An important criterion for evaluating alternative methods of seasonal adjustment is how close initial 

estimates are to the results of subsequent revisions. Users of seasonally adjusted data are often most 

interested in current information. Thus, it is desirable that the initial seasonally adjusted estimates 

be as close as possible to the improved estimates made after more data become available. Even 

though the revisions currently being released for the 2019 seasonally adjusted data are not final, the 

first revisions are usually the largest and often indicate the direction of subsequent revisions. 

Table 1 shows the civilian unemployment rates for January to November 2019, as first published 

and as revised. The seasonally adjusted unemployment rate did not change for any month in 2019. 

(Note that December 2019 is the final month of the series and has no revision.) 
2

Table 1. Seasonally adjusted unemployment rates in 2019 and change due to revision

January ......................................... 4.0 4.0 0.0

February ..................................................... 3.8 3.8 0.0

March ...................................................... 3.8 3.8 0.0

April ............................................. 3.6 3.6 0.0

May ................................................. 3.6 3.6 0.0

June ..................................................... 3.7 3.7 0.0

July .............................................. 3.7 3.7 0.0

August .......................................... 3.7 3.7 0.0

September ............................................ 3.5 3.5 0.0

October ........................................ 3.6 3.6 0.0

November ....................................................................................................... 3.5 3.5 0.0

Month As first

published As revised Change

New seasonally adjusted series 

With the publication of The Employment Situation for January 2020 on February 7, 2020, two not 

seasonally adjusted series currently displayed in Summary table A—persons marginally attached to 

the labor force and discouraged workers—will be replaced with new seasonally adjusted series. The 

new seasonally adjusted series will be available in the BLS online database back to 1994. 

Persons marginally attached to the labor force and discouraged workers are inputs into three 

alternative measures of labor underutilization. Therefore, with the release of data for January 2020, 

data for U-4, U-5, and U-6 will reflect the new seasonally adjusted series. Revised data back to 

1994 will be available in the BLS online database. 

With the release of data for July 2019, seasonally adjusted labor force data for all veterans, male 

veterans, all nonveterans, and male nonveterans became available in the BLS online database. The 

adjusted series for these four groups are the labor force, the labor force participation rate, employed 

persons, the employment-population ratio, unemployed persons, the unemployment rate, and 

persons not in the labor force. Seasonally adjusted data for veterans and nonveterans are available 

back to 2003. 

Availability of revised series 

These revisions replace the seasonally adjusted estimates previously published. Revised historical 

seasonally adjusted labor force data are available in various forms on the BLS website at 

www.bls.gov/cps/data.htm, including text file access at https://download.bls.gov/pub/time.series/ln/

to all of the revised data. The seasonally adjusted data last published for 2014 and earlier years were 

not further revised.