ASA Survey Methodology


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. The participants provide employment, sales, and payroll data on the most recent quarter and, to ensure validity and continuity, the relevant previous quarters. 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. 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 temporary and contract employment trends. The index survey methodology essentially mirrors that of the quarterly ASA Staffing Employment and Sales Survey.

ASA Staffing Index values, based on 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. Similar to the quarterly ASA Staffing Employment and Sales Survey, percentage changes in employment are derived by weighting responses according to company size categories.

Three metrics are published each week. The first is the index value itself, which depicts staffing employment trends over time. The second and third are the weekly and year-to-year percent changes in staffing employment. All three numbers are posted throughout the ASA website.

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.


Both the quarterly ASA Staffing Employment and Sales Survey and the weekly ASA Staffing Index rely on periodic benchmarks from the U.S. Census Bureau. When developing the quarterly survey methodology in 1992, DRI used the 1987 Economic Census of service industries as well as several other sources in estimating industry size and market share weights—long before the introduction of the North American Industry Classification System.

Data from the 1997 census, the first to use NAICS, more clearly delineated “temporary help services” than the Standard Industrial Classification it replaced. Using the 1997 NAICS-based census also provided better comparability and continuity of data for the 1990 to 2002 period than the original DRI estimates, particularly given that the principal interest in the results of the quarterly survey has been changes over time rather than absolute levels of employment, sales, and payroll.

Data from the 2002 census were used as benchmarks for the quarterly survey results from 2002 through 2006, while the 2007 census data were used to benchmark quarterly survey results from 2007 through 2011.

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).

In 2011, given newly released benchmark data from the 2007 Economic Census, 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 2012 Economic Census Core Business Statistic Series, released in March 2016, was used to revise quarterly survey results from 2008 through 2015 and the index values were revised from its inception in 2006 through 2015.

Research Partner

The quarterly ASA Staffing Employment and Sales Survey and the weekly ASA Staffing Index are administered by ASA corporate partner ClearlyRated.