Evaluating the 1990 Projections of Occupational Employment
Rosenthal, Neal H., Monthly Labor Review
The Bureau of Labor Statistics occupational projections are a valuable resource for counselors, students, and others concerned with the future occupational composition of the U.S. labor force. The development of these projections requires careful analysis of large amounts of data to identify occupational employment trends and the factors causing them, and to determine a likely course for those trends in the future.
However, there is inherent uncertainty in any projection. Consequently, BLS periodically evaluates the results of past projections to gauge how well the projections tracked against actual occupational employment change. This process provides users of occupational projections with information about the accuracy of projections of the future growth of occupations that may be valuable in career decisionmaking, education planning, and other endeavors. In addition, analysts developing projections gain insight into the process that resulted in errors or accurate projections that can be used in the development of future projections. Thus, BLS considers evaluation to be an important stage of the projections program.
The last BLS occupational projections to be formally evaluated were the projections to 1980 from a base year of 1970.(1) The projections to 1985 were not evaluated because they were based on the 1970 census occupational classification system, which was so different from the classification system in use in 1985 that the projected and actual data were not comparable. The projections for the period 1978-90 also were not evaluated because they were not used in any edition of the BLS Occupational Outlook Handbook and, as indicated below, assessing information presented in the Handbook is an important aspect of the evaluation. However, projected 1990 employment in the 1978-90 set of projections(2) was nearly identical to the 1980-90 projections evaluated in this article. Consequently, the evaluation of those projections would be virtually the same as that presented here, because the differences between projected and actual 1990 employment were used as the basic measure of accuracy.
Like the previous evaluations of occupational projections, this article identifies the errors and accuracies of projections for major occupational groups and for a selected number of detailed occupations; discusses the major causes of error for many of the occupations having the largest errors; and compares the errors with those found in earlier projections. In addition, it discusses some of the technical concerns about the accuracy of the evaluation process itself, summarizes some of the lessons learned that can be used to benefit future projections efforts, and comments on an evaluation of the projections made by researchers outside of BLS.
Major occupational groups
Total employment for 1990 was projected very accurately, as actual employment was less than 1 percent greater than projected.(3) Among the major occupational groups, the 1990 projections were on target for service occupations, with projected employment less than 1 percent more than actual employment. The one group to experience an employment decline--agriculture, forestry, fishing, and related occupations--was correctly projected to be the only major occupational group to lose jobs. Although the decline was somewhat less than projected, the projection was only 6 percent lower than actual employment. The projections also were reasonably accurate for the following major groups: executive, administrative, and managerial; technicians and related support; and administrative support occupations, including clerical. The difference between actual and projected employment for these groups ranged from 3.1 percent to 6.0 percent. (See table 1.)
Projection errors were fairly large for salesworkers and professional specialty occupations, the two fastest-growing occupational groups between 1980 and 1990. The marketing and sales group had the largest projection error. …