In comparing QCEW data for different industries, areas and over time, is there anything users should be cautious about?
There are four possible types of series breaks in QCEW series that users should be aware of: industry coding changes, unemployment insurance coverage changes, geographic definition changes, and size class changes. Industry changes: Since the introduction of 2001 data, the QCEW data have been coded according to the North American Industry Classification System, either NAICS 2002, which was used for the data up through 2006, or NAICS 2007 which will be used for data for the period from 2007 forward. NAICS is the statistical classification standard underlying all establishment-based Federal economic statistics classified by industry. Before 2001, QCEW data were coded according to the Standard Industrial Classification (SIC) system. QCEW data for the period from 1975 through 1987 were coded according to the 1972 SIC Manual (including the 1977 amendments). QCEW data for the period from 1988 through 2000 were coded according to the 1987 SIC Manual. Due to the differences in the classificatio
