In This Chapter |
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Chapter 2.
Employment, Hours, and Earnings from the Establishment
Survey
Sample
Design In June of 2003, BLS completed a comprehensive
sample redesign of its monthly payroll survey, which
coincided with the conversion of all CES series to industry
coding based on the 2002 North American Industry
Classification System (NAICS). The original CES survey was a
quota sample whose inception in the 1940s predated the
introduction of probability sampling as the internationally
recognized standard for sample surveys.
The design is a stratified, simple random sample of
worksites, clustered by UI account number. The sample
strata, or subpopulations, are defined by State, industry,
and employment size, yielding a State-based design. Sampling
rates for each stratum are determined through optimum
allocation, which distributes a fixed number of sample units
across a set of strata to minimize the overall variance or
sampling error on the primary estimate of interest, the
statewide total nonfarm employment level.
The sampling frame, and the CES sample itself, are
updated twice a year with new quarters of UI-based universe
data. This helps to keep the sample up-to-date by adding
firm births and deleting business deaths. In addition, the
design specifies an annual update process, which includes
sample frame maintenance and the redrawing of the entire
sample for the first quarter of each year. Frame maintenance
provides for the updating of industry, employment size class,
and metropolitan area designations and for the merging of
semiannual birth samples into the overall frame.
Next: Estimating
Procedures
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Last Modified Date: February 9, 2004
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