Methodology of ASA Economic Surveys

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 a third of 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 / McGraw–Hill in 1992. DRI conducted a census of ASA members and 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 more than 100 small, medium, and large staffing companies that together provide services in virtually all sectors of the industry and together account for nearly half of total U.S. staffing industry sales. 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 aggregate benchmark estimates for temporary and contract staffing employment, sales, and payroll.

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 work week, 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. Like 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 would 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.

Benchmarks

Both the quarterly ASA Staffing Employment and Sales Survey and the ASA Staffing Index weekly survey rely on periodic benchmarks from the U.S. Census Bureau. In 2011, given newly released benchmark data from the 2007 Census of Business, ASA revised historical figures for staffing employment, sales, and payroll back to 1990 and ASA Staffing Index values to the index’s inception in 2006.

The 2007 census data were used as benchmarks for the quarterly survey results from 2007 to present. The 2007 census data were also used as benchmarks for the index back to 2006; 2006 and 2007 were peak—and similar—years for the staffing industry, and the index covered only the last six and a half months of 2006, which were much more like 2007 than 2002, the previous census year (and hence the next available benchmark).

Data from the 2002 census were used as benchmarks for the quarterly survey results from 2002 through 2006. Data from the 1997 census, the first to use the North American Industry Classification System, more clearly delineated “temporary help services” than the Standard Industrial Classification it replaced.

In developing the quarterly survey methodology in 1992, DRI used the 1987 census of service industries as well as several other sources in estimating industry size and market share weights—long before the introduction of NAICS. Using the 1997 NAICS-based census provides better comparability and continuity of data for the 1990 to 2002 period than the original DRI estimates, particularly given the principal interest in the results of the quarterly survey has been changes over time rather than absolute levels of employment, sales, and payroll.

Research Partner

The quarterly ASA Staffing Employment and Sales Survey and the ASA Staffing Index weekly survey have been conducted by ASA research partner Inavero since 2007. Inavero also conducts the annual ASA sector benchmarking survey, annual membership survey, and annual Staffing World^® satisfaction survey. ASA and Inavero are also working together to plan future staffing industry research projects.