1

U.S. Bureau of Labor Statistics 

Current Population Survey (CPS) 

Technical Documentation 

January 2023

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 2023

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) data series by including 

another full year of data in the estimation process.

Following this annual reestimation, BLS revises the seasonally adjusted national household survey 

labor force estimates for the previous 5 years. 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 2022 estimates

This year’s revisions incorporate data through December 2022 and provide revised estimates for 

January 2018 through November 2022 for all previous seasonally adjusted labor force series. (Many 

data series had large outliers after the onset of the coronavirus (COVID-19) pandemic. Therefore, 

starting in 2020, BLS staff made some modifications to seasonal adjustment models as needed for 

series with large outliers. These changes, which are described in the following section, were 

reviewed as part of the annual reestimation process.)

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 generated after more data become available. Even 

though the revisions currently being released for the 2022 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 2022, as first published 

and as revised. The seasonally adjusted unemployment rate was revised slightly for 1 month in 

2022. (Note that December 2022 is the final month of the series and has no revision.)
2

Table 1. Seasonally adjusted unemployment rates in 2022 and change due to revision

Month 

As first 

published As revised Change 

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

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

March.......................................... 3.6 3.6 0.0 

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

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

June.............................................. 3.6 3.6 0.0 

July.............................................. 3.5 3.5 0.0 

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

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

October........................................ 3.7 3.7 0.0 

November.................................... 3.7 3.6 -0.1 

Extension of seasonal adjustment to additional series

No new seasonally adjusted series were added for 2023.

Pandemic-related modifications to seasonal adjustment models

The onset of the pandemic early in 2020 had a marked impact on many data series from the

household survey. Since April 2020, BLS staff have tested household survey data series for outliers 

to determine whether any changes were needed to the seasonal adjustment models. BLS staff 

determined that the vast majority of household survey data series had large outliers and made 

adjustments as needed to the models used in seasonal adjustment processing to account for them.

For more information on the modifications, see Revisions to seasonally adjusted national household 

survey labor force series effective in January 2022.

Availability of revised series

These revised estimates 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 as text files at https://download.bls.gov/pub/time.series/ln/. 

The seasonally adjusted data last published for 2017 and earlier years were not further revised. (Not 

seasonally adjusted data were not subject to revision.)