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

2. Another occupation showing an increase of over 1000 percent was the residual category “Physical
scientists, all other” (1131.4 percent). This apparent increase, however, may be more due to a
coding anomaly than to a real change in the number of physical scientists. Often in the census,
respondents do not provide enough information for accurate assignment to a category. In 1990, if a
person said he or she was a “scientist” without specifying exactly what kind of scientist, the
response was assigned to a processing step called “problem referral,” where a coder had to make a
judgment about the correct code to assign, based on the industry or other information provided.
These unspecified responses were probably spread among several categories for scientists. In
2000, however, the new SOC and the Census index assigned all unspecified scientists to the
category for “Physical scientists, all other.” This decision to simplify the coding process probably
inflated the number of people assigned to the residual category for physical scientists in Census
2000.
3. In the group “Production occupations,” a computer-related occupation with a very large increase
was “Computer control programmers and operators” (731.5 percent). Although this occupation is
not part of the “Computer specialists” major group, many workers in this category develop
programs to control machining or processing by automatic machine tools, equipment, or systems.
In other words, the change in this occupation category may reflect an increase in the use of
robotics and other automated processes in production-type industries, and the need for people who
can program and operate those processes.
4. Other categories with high percentage increases, each tripling or more from 1990 to 2000, were:
“Financial examiners” (482.8 percent); “First-line supervisors/managers of correctional officers
(360.7 percent); “Physician assistants” (356.7 percent) 8 ; “First-line supervisors/managers of
personal service workers (337.9 percent); and “Industrial production managers” (226.7 percent).
5. Most Census 2000 products do not show data for occupation categories with fewer than 10,000
people nationwide. Among the categories over this threshold in 2000, the ones showing the
greatest losses from 1990 to 2000 were: “Aircraft structure, surfaces, rigging, and systems
assemblers” (-81.1 percent); “Railroad brake, signal, and switch operators” (-69.7 percent);
“Textile, apparel, and furnishings workers, all other” (-61.6 percent); and “Textile cutting machine
setters, operators, and tenders”(-60.9 percent).
ACCURACY AND RELIABILITY OF THE DATA
As from any sample, the proportions (conversion factors) shown in the comparability tables are subject to
sampling error, especially when the numbers for a detailed category are very small. Furthermore, since the
base sample is from 1990, it reflects the industrial and occupational composition of the labor force at that
time. Because industries and occupations change over time, the sample may be less useful for other time
periods. Surveys and other databases may measure the industrial and occupational distribution of the labor
force differently from the decennial census. Therefore, although the conversion factors contained in this
paper can be used for other data sources, the conversion may not be as accurate as for the data from the
1990 census. Remember also the point described earlier in this paper that these factors will vary in
accuracy for each sex, race, geographic area, or other characteristic.
8 This category includes emergency medical technicians and paramedics.
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