NAICS, SIC, and Industry Classification Data

Business industry classifications come from self-reported data, typically through registration or insurance-related transactions. These classifications are quite broad, and companies in higher-risk occupations often use multiple industry identifiers to reduce their workers' compensation insurance liability. There is no central authority governing these categories, so the Primary_industry field should be taken with a grain of salt. NAICS codes are a more modern and specific version of SIC codes, but not as widely adopted, which is why both are included in the data.