Frequently Asked Questions

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FAQ

How can I convert NAICS-based data into the SIC categories I am familiar with? 

  • It's not easy. If you are trying to compare data for two years, use data that are classified on the same basis where possible. For example, 1997 Economic Census data, while mostly published by NAICS, includes one report with both 1997 and 1992 data by SIC: Comparative Statistics.
  • Fewer than half of all 4-digit SIC categories have direct NAICS counterparts or can be reconstructed by adding whole NAICS codes together. Another group can be approximated within 3 percent of sales using whole NAICS codes. You can identify which these are by looking for the Comparable(comparable) or Almost comparable(almost comparable) symbols in the Bridge Between NAICS and SIC. For the remaining SIC codes, identified with Not comparable(not comparable), the bridge data allow you to determine what proportions of particular NAICS contribute to a given SIC. Note that any proration you do is subject to considerable error, and prorating on sales or employment may give significantly different results.

(FAQ105)

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