Current Population Survey (CPS)

Technical Documentation 

January 2019 

 

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 2019

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 revises the previous 5 years of seasonally adjusted national 

household survey labor force data. The revised historical data are released in January each year, 

coinciding 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 https://www.bls.gov/cps/seasonal-adjustment-methodology.htm. 

Changes effective in January 2019 

Revisions to 2018 estimates

This year’s revisions incorporate data through December 2018 and provide revised labor force 

estimates for January 2014 through November 2018 for all previously published seasonally adjusted 

labor force series. Currently, there are 153 series that are directly seasonally adjusted and many 

more that are derived from these 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 2018 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 2018, as first computed 

and as revised, and there were three small revisions. Note that December 2018 is the final month of 

the series and has no revision. 
2 

Table 1. Seasonally adjusted unemployment rates in 2018 and change due to revision

January ......................................... 4.1 4.1 0.0

February ......................................... 4.1 4.1 .0

March ............................................. 4.1 4.0 -.1

April ............................................. 3.9 3.9 .0

May ................................................ 3.8 3.8 .0

June ................................................ 4.0 4.0 .0

July .............................................. 3.9 3.9 .0

August .......................................... 3.9 3.8 -.1

September ...................................... 3.7 3.7 .0

October ........................................ 3.7 3.8 .1

November ...................................... 3.7 3.7 .0

Month As first

computed As revised Change

Extension of seasonal adjustment to additional series 

No new seasonally adjusted series were added in 2019. 

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 2013 and earlier years were 

not further revised.