Methodology American Staffing Association
ASA Staffing Employment and Sales Survey
The American Staffing Association provides the only survey-based quarterly estimate of U.S. temporary and contract staffing sales. The quarterly ASA staffing employment and sales survey—which covers approximately 10,000 establishments (about half the industry)—also tracks employment and payroll, with results that parallel the establishment surveys of the U.S. Bureau of Labor Statistics.
The survey is used to estimate total industry employment, sales, and payroll, based on a model developed for ASA by Standard & Poor's DRI in 1992. DRI conducted a census of ASA members as well as a survey of selected nonmember firms. Using this and related government data, DRI prepared annual estimates for 1990 and 1991, and a stratified-panel, survey-based estimation model to be used quarterly from 1992 forward.
To preserve the confidentiality of individual company responses, a market research firm collects and tabulates the data and reports only aggregate results to ASA. Survey participants include 100 to 200 small, medium, and large staffing companies that together provide services in virtually all sectors of the industry. The participants provide employment, sales, and payroll data on the most recent quarter and, as part of the panel design to ensure validity and continuity, the previous quarter. Responses are stratified by company size and used to derive growth rates for each stratum. Strata for each metric are weighted based on the proportionate market share of similarly sized companies to derive overall growth rates for the industry as a whole. These growth rates are applied quarter-by-quarter to the aggregate estimates for temporary help employment, sales, and payroll that had been calculated for the benchmark quarter (initially by DRI in 1992).
When 1997 U.S. Economic Census data became available in 2000, ASA commissioned DRI to revalidate, update, and rebenchmark the model. Data from the economic census and the Omnicomp Group Inc. were used to newly calculate a benchmark quarter for 1997, from which all previous estimates were revised.
Similarly, when the 2002 U.S. Economic Census data became available in 2005, ASA commissioned the Lewin Group, an economic research firm, to rebenchmark the survey results based on DRI's model. Again, industry data from the economic census and the Omnicomp Group Inc. were used to establish a benchmark quarter for 2002; all previous estimates were revised accordingly.
ASA Staffing Index
The ASA Staffing Index tracks weekly changes in temporary and contract employment. The index survey methodology mirrors that of the quarterly ASA staffing employment and sales survey.
Survey results are typically posted nine days after the close of a given workweek, providing a near real-time gauge of staffing industry employment and overall economic activity.
Participants include a stratified panel of small, medium, and large staffing companies that together provide services in virtually all sectors of the industry and account for more than one-third of U.S. staffing industry establishments and sales. As with the quarterly ASA staffing employment and sales survey, percentage changes in employment are derived by weighting responses according to company size categories.
Two numbers are reported weekly. The first is the weekly percentage change in staffing employment. The second is the index itself, which shows staffing employment trends over time. Both numbers are posted on the home page of the ASA Web site, americanstaffing.net
The index is calculated by applying the weekly percentage change in employment to a reference value set at 100 for the week of June 12, 2006. The index reflects the percentage change in employment since that reference week—so when the index reaches 200, staffing employment will have doubled since June 2006. The index does not estimate total industry employment; the quarterly ASA staffing employment and sales survey provides that data.
ASA developed the index with the expertise of the Lewin Group, an economic research firm.
|