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Mass Layoff Statistics

Mass Layoff Statistics—Data Revision Procedure

Every five years, the North American Industry Classification System (NAICS) is updated to reflect changes in the U.S. economy, recognize new and emerging industries, and strive for international compatibility. In the MLS program, industry information for employers is obtained from the BLS Quarterly Census of Employment and Wages (QCEW) program.

NAICS 2007 Changes

Revisions associated with converting to the 2007 version of NAICS were limited in scope. Of the 1,179 industries used by BLS under NAICS 2002, 21 industries were revised. Eight industries directly transferred to one NAICS 2007 code, while the remaining 13 industries split into more than one NAICS 2007 code. For many of the “split” industry revisions, the original was often retained with minor definitional changes. A complete list of NAICS 2007 industries with further information on the changes associated with moving from the 2002 NAICS is available on the Census Bureau’s NAICS page, which can be accessed at

Implementation in the MLS Program

The MLS program implemented the 2007 version of NAICS beginning with January 2008 mass layoff data, released on February 27, 2008. The first publication of quarterly extended mass layoff data using NAICS 2007 were issued with the release of first quarter 2008 data on May 15, 2008. MLS data are published at the major sector level and the subsector level (3-digit NAICS).

Layoff events prior to 2008 with one of the eight NAICS 2002 codes that directly transfer to a NAICS 2007 industry were changed to the NAICS 2007 industry in order to minimize the number of data series breaks. This resulted in slight, one-time revisions to NAICS 518 (data processing, hosting and related services) and NAICS 519 (other information services).

Pre-2008 events with one of the thirteen NAICS 2002 industries that split into more than one NAICS 2007 industry were not changed. Therefore, data for these industries beginning in 2008 are not strictly comparable to pre-2008 information, though differences are not likely to be significant. Affected industries at the major sector level included administrative and waste services, finance and insurance, professional and technical services, and real estate and rental and leasing. At the subsector level, 15 industries were affected.

Previous Industry Changes in the MLS Program

The MLS program switched to the North American Industry Classification System (NAICS) in 2002. More information on this change is available at


Last Modified Date: May 15, 2008