The Relationship Between The 1990 Census and ... - Census Bureau

The Relationship Between the 1990 Census and Census 2000 Industry and
Occupation Classification Systems
INTRODUCTION
This paper describes the changes in the industry and occupation classification systems used in the 1990
Census of Population and Housing (1990 Census) and the classification systems used in Census 2000. As
a result of these changes, many 2000 industry detailed categories and major groups and most 2000
occupation detailed categories and major groups are not comparable to similar categories and groupings in
the 1990 and earlier censuses.
The Census Bureau provides data on industries and occupations at several different levels of detail on
various data products (also called data sets), which change from census to census. For Census 2000 data
analysts can find industry and occupation tables on data sets called Summary File (SF)-3, SF-4, the Equal
Employment Opportunity (EEO) File, and Public Use Microdata Samples (PUMS). These products are
similar to counterparts produced from the 1990 Census. Some of these 1990 and 2000 products are
available on the Census Bureau’s website called American FactFinder (see www.census.gov).
For Census 2000 the tables found on SF-3 present the industry and occupation data in very aggregated
groupings. These tables include “profiles,” which show only 13 industry and 6 occupation groups, and
“detailed tables,” which show 20 industry and 33 occupation groups. In the SF-4 tables the level of detail
increases to 90 unique industry and 93 unique occupation categories. The EEO File and “5-percent”
PUMS provide data for 471 detailed occupation categories, and finally, the “1-percent” PUMS shows the
most detail possible: 509 occupations and 265 industries. For more information about these Census 2000
products and how they compare to their 1990 counterparts, see “Sources of Industry and Occupation
Data” below.
Even though the American FactFinder and other sources provide data for both the 1990 Census and
Census 2000, data analysts cannot compare the industry and occupation categories directly across the two
census years. The wording of the categories is different, and, even when the words appear to be the same,
the definitions of the categories are sometimes different. For example, major parts of “Retail trade” and
“Entertainment and recreation services” were defined differently in 1990 than in 2000, even though these
words appear in industry tables from both censuses. As another example, “Managers” and “Farming
occupations” were defined differently in 1990 than in 2000, even though these words appear in
occupation tables from both censuses. These differences were caused by the revisions to the North
American Industry Classification System (NAICS) and to the Standard Occupational Classification
(SOC). The Census 2000 industry and occupation categories were derived from these two standard
classifications, respectively. See the “History” section below for more details.
This report is designed to help analysts compare 1990 and 2000 census data from any of these data
products by quantifying the relationship between the two sets of classification systems. Included are
detailed tables called “crosswalks,” which show the proportional flows for individual industry and
occupation categories between the two census years, and tables comparing the different groupings found
on SF-3, SF-4, the EEO File, and the PUMS. The Census Bureau derived these proportions from a sample
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