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Mode Effects Analysis of Major Labor Force Estimates

Jenny Thompson


The official monthly civilian labor force estimates from January 1994 onward are based on data from a comprehensively redesigned Current Population Survey (CPS). The redesign incorporates changes in the basic questionnaire and collection methodology. Bregger and Dippo (1993) discuss the motivation for this redesign.

To gauge the effect of the CPS redesign on published estimates, a Parallel Survey (PS) was conducted using the new questionnaire and collection procedures from July 1992 to December 1993. Annual average estimates from the PS were used to examine the effect of the CPS redesign on major labor force estimates. Polivka (1994) presents a comparison of the labor force estimates from the PS and CPS during 1993. Kostanich and Cahoon (1994) further consider the possible influence of the differences in the two surveys' designs on these comparisons.

A secondary consideration was an investigation into the possible effect of selected factors associated with the new questionnaire or collection mode on major labor force estimates. Special studies were embedded within the CPS and the PS during the same time period to provide data for testing hypotheses about the effects of these methodological differences on labor force estimates. The resultant hypothesis tests attempted to link the differences in annual average major labor force estimates between CPS and the PS to the presence of specified collection mode differences.

This report centers on four possible effects: two centralized telephone interviewing effects and two new questionnaire effects. Three of the four hypothesis tests used subnational estimates of CPS and PS data and were not necessarily representative of the national differences. The other hypothesis test used national estimates computed from approximately one fourth of the full sample (for both surveys).

The Background section of this report provides an overview of the two surveys' designs, a description of the estimates and variance estimates, descriptions of hypothesis testing methodology, and detailed descriptions of the tested hypotheses. The Results section presents the hypothesis tests for major labor force characteristics. The Summary section provides general conclusions.