The distribution of the GPO of private industries is based on the Standard Industrial Classification (SIC), a system that provides a classification for establishments (that is, economic units, generally at a single physical location, where business is conducted or where services or industrial operations are performed). Establishments are classified into an SIC industry on the basis of their principal product or service. Thus, establishment data cover both the principal products included in the SIC and the products of these establishments that are primary to other SIC industries. Industrial distributions for government activities are not provided; separate estimates are shown for the activities of the Federal Government, of State and local governments, and of government enterprises./1/
The GPO estimates of private industries for 1987 forward are presented on the basis of the 1987 SIC. Estimates for earlier years are presented on the basis of the 1972 SIC; they have not been adjusted to the 1987 SIC because of a lack of adequate source data. To provide a link between the two classifications, the estimates for 1987 are also presented on the basis of the 1972 SIC. (Industry source data for years after 1987 are available only on the 1987 SIC basis.) For the following 1987 SIC industries, there are significant differences between the 1972 SIC and the 1987 SIC at the level of detail that GPO is presented: In manufacturing, electronic and other electrical equipment (SIC 36) and instruments and related products (SIC 38); in communications, telephone and telegraph (SIC 481, 482, and 489) and radio and television (SIC 483 and 484); in FIRE, depository institutions (SIC 60) and nondepository institutions (SIC 61); and in services, business services (SIC 73) and other services (SIC 84, 87, and 89).
1. For additional information on industrial distributions presented in the NIPA's, see U.S. Department of Commerce, Bureau of Economic Analysis, National Income and Product Accounts of the United States: Volume 2, 195988 (Washington, DC: U.S. Government Printing Office, September 1992): M-12.