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