New Seasonal Adjustment Factors

for Household Data Series

Robert J. Mcintire

S

emiannually, the Bureau of Labor Statistics publishes

the factors to be used during the following 6 months

for seasonal adjustment of the major labor force series.

Table I presents the seasonal adjustment factors for the 12

major labor force components for the period July-December

1999. The factors for these components for the first 6 months

of 1999 were published in the January 1999 issue of

Employment and Earnings. The 12 seasonally adjusted series

which result from the application of these factors are used

in the computation of the seasonally adjusted figures for the

national overall levels of labor force, employment, and

unemployment and the overall unemployment rate.

The new seasonal factors have been extrapolated using

the X-II ARIMA program with data from January 1990

through June 1999 for each series. The ARIMA models used

Robert J. Mcintire is an economist and Chief of the Division of Data

Development and Publications, Office of Employment and Unemployment

Statistics, Bureau of Labor Statistics.

were the same as those used earlier in the year for the

extrapolation of the factors for January through June; they

were identified in the January 1999 issue of this publication.

The historical seasonally adjusted data. including the first 6

months of 1999, will not be revised until the beginning of

2000.

Because of the changes introduced at the beginning of

1994, 1997, and 1999 in the survey and the processing procedures on which the labor force series estimates are based, I

prior adjustment factors were used in these X-II ARIMA

runs to link the pre-1994, pre-1997, and/or pre-1999 data

with the subsequent data for purposes of seasonal adjustment. Without prior adjustment, those changes could. have

caused distortion in the seasonal decomposition. The pre1994 and pre-1997 prior adjustment factors used in these

runs were the same as those used in the runs that provided

'The changes were described in articles in the February 1994, 1997,

and 1999 issues, respectively, of this publication.

Table 1. Prior adjustment and July-December 1999 seasonal adjustment factors for the 12 major civilian labor force components

Prior Seasonal adjustment factors

Procedure and series adjustment

factors July August September October November December

Multiplicative adjustment

(Divide factor into original value)

AgricuHural employment:

Men, 20 years and over .................................... (') 1.087 1.060 1.059 1.045 .989 .929

Women, 20 years and over ............................... .776 1.122 1.099 1.086 1.032 .968 .930

Men, 16 to 19 years .......................................... .860 1.590 1.439 1.046 .858 .752 .697

Women, 16 to 19 years ..................................... .853 1.540 1.509 1.086 .844 .777 .646

NonagricuHural employment:

Men, 20 years and over .................................... 2.996, 1.003 1.005 1.006 1.000 1.004 1.004 1.001

Women, 20 years and over ............................... 3.996 .989 .989 1.002 1.007 1.009 1.009

Unemployment:

Men, 20 years and over .................................... .938 .969 .921 .929 .899 .920 1.008

Women, 20 years and over ............................... .976 1.064 1.098 1.035 .972 .957 .887

Additive adjustment

(Subtract factor from original value)

NonagricuHural employment:

Men, 16 to 19 years .......................................... -68 728 415 -147 -79 -98 -125

Women, 16 to 19 years ..................................... "96 646 376 -168 -186 -139 -33

Unemployment:

Men, 16 to 19 years .......................................... -47 158 -28 -60 -38 -54 -92

Women, 16 to 19 years ..................................... (') 136 -23 -24 -47 -26 -64

, No prior adjustment was done.

2 For this series, the factors are pre-1997 and pre-1999. The first factor shows

the adjustment of pre-1997 data relative to subsequent data; the second factor

shows the adjustment of pre-1999 data relative to subsequent data. The actual

net adjustment to pre-1997 data is the product of the two factors.

3For this series, the prior adjusted period was pre-1999 rather than pre1994.

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the factors for January through June. The pre-1999 prior

adjustment factors are new in these runs because these are

the first runs that include data reflecting the changes in population controls introduced in January 1999. Prior adjustment

factors to control for those changes were found to be warranted for 16 series, including two of the 12 major components, and IO of those 16 series now have two prior adjustment points (pre-I 994 and pre-I 999 , or pre-I 997 and pre1999). The prior adjustment factors for the 12 major components are shown in table 1 alongside the seasonal factors.

More detailed information on the seasonal adjustment

procedures and the revision of historical data is included in

"Revision of Seasonally Adjusted Labor Force Series,"

Employment and Earnings, January 1999.

Data for any of the several hundred seasonally adjusted

labor force series and the July-December 1999 seasonal

adjustment factors for any of the other independently

adjusted series-there are about 170 in addition to the 12

major components-may be obtained from BLS upon

request. Requests for data or inquiries concerning seasonal

adjustment methods or the availability of machine-readable

files of other labor force data should be addressed to the

Division of Data Development and Publications, Bureau of

Labor Statistics, Washington, D.C. 20212-000 I.

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