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

The second review of the 1990 Census Sample, however, revealed exceptions to this assumption. As
described above in the section about the 2000 Classified Indexes, there are legitimate reasons why 1990-
2000 code combinations can appear in a sample of responses that do not appear in the indexes of industry
and occupation titles. When the review uncovered these exceptions, the records containing those
exceptions were restored to the sample, and their 1990-2000 code combinations were deemed
“legitimate,” after all.
Using the revised list of legitimate 1990-2000 code combinations, the 1990 Census Sample records for
each 1990 code containing these combinations were used to re-tabulate the percentages of each 1990
category going to each 2000 category. These percentages became the conversion factors applied to the
entire 1990 ECLF as shown in the tables that accompany this paper.
To a large extent, the analysis of the occupation data shown in this study followed up on a similar analysis
done by staff at the Bureau of Labor Statistics (BLS), 6 who used the same double-coded index of
occupations, and the earlier version of the double-coded 1990 occupation sample before the last round of
corrections to the sample. Their methodology eliminated many more combinations of 1990 and 2000
codes, particularly when the sample providing those combinations was very small. The final conversion
factors shown in this Census Bureau report are much more detailed, and sometimes differ substantially
from those shown in the BLS study.
Explanation of the Tables
Tables 1-3 and 8-9 in this report show 1990 census data for the total civilian labor force in terms of the
1990 and 2000 census classification structures. Tables 4-7 and 10-11 show data for the employed. The
conversion factors described above are reflected in all the tables, even those that do not display the
detailed factors.
Tables 1 and 2 include all the categories assigned to the labor force in each census:
1990 industry: 236
2000 industry: 265
1990 occupation: 501
2000 occupation: 509
Table 1 shows the number of people from the 1990 ECLF in each 1990 detailed census industry category,
the number of these people that would be assigned to each 2000 detailed census industry category, and the
conversion factors that led to this redistribution of each 1990 category to each 2000 category. Table 2 is
the corresponding occupation table. These tables display both a code and a description of each category
for both censuses.
Example 1 (Table 1). 1990 Census industry category 272, “Primary aluminum industries
(manufacturing)” split into two Census 2000 categories: 73.3 percent went to 2000 category 268,
“Aluminum production and processing,” and 26.7 percent went to category 277, “Foundries.”
Example 2 (Table 2). 1990 Census occupation category 106, “Physicians’ assistants,” split into three
Census 2000 categories: 35.4 percent went to 2000 category 311, “Physician assistants,” 41.7 percent
6 Eck, Alan: Memorandum to Tom Nardone, “Observations on 2000 Census of Population based occupational employment
estimates.” Bureau of Labor Statistics internal report, January 24, 2002.
13