Abstract
Stephanie Cano, Patricia Getz, Jurgen Kropf, Stuart Scott, and George Stamas (1996) "Adjusting for A
Calendar Effect in Employment Time Series," Proceedings
of the Section on Survey Research, American Statistical
Association.
The Bureau of Labor Statistics Current Employment
Statistics (CES) program is a monthly survey of nearly
400,000 business establishments nationwide; its reference
period is the pay period including the 12th of each month. Of
paramount importance to most CES data users are
over-the-month changes in total nonfarm employment levels,
thus the seasonal adjustment of these data critically affects
the analysis of national employment trends. This study
investigates a calendar effect which may cause difficulties
in interpreting movements in the current seasonally adjusted
series. The effect arises because there are sometimes 4 and
sometimes 5 weeks between the reference periods in any given
pair of months (except February/March). This varying interval
effect is estimated by an ARIMA model with regression
variables, using the Bureau of the Census X-12 ARIMA
procedure. Estimates of the interval effect are tested for
significance. Series estimated with and without the interval
adjustment are compared for smoothness and stability across
successive time spans. Differences between over-the-month
employment changes as previously published and as estimated
with interval effect modeling are also examined.
Last Modified Date: July 19, 2008
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