Persons holding science and engineering doctorates have a high rate of participation in the labor force. Of the estimated 582,080 persons under the age of 76 who had received a doctorate in science or engineering from an U.S. institution, there were 518,440 (89 percent) employed during the week of April 15, 1997. An additional 6,390 (1 percent) were unemployed; and 57,250 (10 percent) were not in the labor force. For scientists and engineers with doctorates, those 55 or older constituted 31 percent of all scientists and engineers, about one-quarter (25 percent) of employed scientists and engineers, 32 percent of the unemployed, and 83 percent of those not in the labor force.
Between 1993 and 1997, the percentage of employed doctoral scientists and engineers who were 55 or older increased from 21 percent to 25 percent while the percentage of all doctoral scientists and engineers 55 or older rose from 26 percent to 31 percent. These increases show that the age distribution of the doctoral science and engineering population over the mid-1990s was becoming increasingly skewed towards older scientists and engineers.At the other end of the age spectrum, the percentage of doctoral scientists and engineers aged 39 or less fell slightly, from 23 percent in 1993 to 22 percent in 1997.
Table 1 shows the labor force status of doctoral scientists and engineers by age. For ages 54 and younger, the employment rate was about 96 percent. For older age groups, the employment rate was lower, due to doctoral scientists and engineers leaving the labor force. However, for doctoral scientists and engineers aged 65-69, about half (53 percent) were still working. At 70-75, about one-quarter (28 percent) remained employed, about half part time. The percentage that was unemployed (~1 percent) varied little across the entire age spectrum.
For all age intervals, employment rates for scientists and engineers with doctoral degrees were somewhat higher than for scientists and engineers whose highest degree was a bachelor's or master's degree. For example, in the group aged 65-69, 34 and 38 percent of those with bachelor's and master's degrees, respectively, as their highest degree were employed, compared with 53 percent of those with U.S.-earned doctorates.
The distribution of employed doctoral scientists and engineers by principal employment sector (education, government, or industry) showed some variation with age (table 2). The largest differences between age groups for both the industry and education sectors were between scientists and engineers aged 60-64 and 65-69 on one hand, and those aged 70-75 on the other. For those aged 70-75, the percentage working in industry, including the self-employed (49 percent), was considerably greater than in the 60-64 and 65-69 age groups (36 percent for both). In contrast, the percentage of employed doctoral scientists and engineers aged 70-75 working in the education sector (43 percent) was smaller than for those ages 60-64 (54 percent) and 65-69 (56 percent). This result may reflect the tendency of retirees from educational institutions to continue to work in industry or be self-employed as consultants or in some other capacity. However, when the results are differentiated further by full-time versus part-time employment, the picture changes somewhat, as will be discussed below in connection with table 3.
The incidence of part-time work is much higher for those over 59, and particularly for those over 64 (figure 1). Part-time workers constituted about 5 to 7 percent of employed doctoral scientists and engineers aged 59 or younger, about 30 percent of those 65-69 and nearly half (48 percent) of those 70-75. Thus, the part-time doctoral science and engineering labor force has a larger proportion of older workers than the full-time labor force. Those 55 or older constituted 45 percent of part-time science and engineering doctoral employees, compared with only 24 percent of all such full-time workers.
The distribution of part-time doctoral science and engineering workers across the three principal employment sectors (education, government, and industry) was roughly the same for those aged 65-75 as for those 64 or younger (table 3). However, among full-time workers, older doctoral scientists and engineers were more likely to be employed in the education sector and less likely to be employed in industry. For doctoral scientists and engineers aged 65-75 and employed in industry, the ratio of full-time to part-time workers was about 50:50; in contrast, about three quarters of doctoral scientists and engineers aged 65-75 in education and government were employed full time. In each of the three employment sectors, the percentage working part time was larger for those aged 65-75 than those 64 or younger, a result consistent with figure 1.
Table 3 also illustrates aspects of self-employment as the primary employment for doctoral scientists and engineers. Some 14 percent of those aged 65-75 who were employed were self-employed, compared with 4 percent of those 64 and younger, indicating that self-employment, such as consulting work, constitutes a more significant aspect of employment for older workers. More than half (57 percent) of self-employed doctoral scientists and engineers aged 65-75 worked part time, versus about a third (32 percent) of those 64 and younger.
A previous analysis summarized in Science and Engineering Indicators: 2000 using 1997 SESTAT data found that those scientists and engineers with doctorates tended to continue to work full time to more advanced ages than their counterparts with bachelor's or master's as their highest degree. By age 63, half of scientists and engineers with bachelor's or master's degrees as their highest degree were no longer working full time whereas for doctoral scientists and engineers, this 50-percent mark was not reached until age 66, three years later. By age 70, about 20 percent of doctoral scientists and engineers were still working full time, compared with 10 percent of scientists and engineers with bachelor's or master's degrees as their highest degree.
The distribution of all employed doctoral scientists and engineers by field of doctoral degree was similar for those 64 and younger and for those 65 to 75 years old (table 4). Among those working part time, the distribution by field of degree showed that a larger proportion of those aged 65-75 had doctoral degrees in the physical sciences (26 percent) than did the younger doctoral scientists and engineers (14 percent). In contrast, a smaller proportion of part-time employees aged 65-75 had doctoral degrees in the social sciences (38 percent) than did younger doctorates (48 percent).
 The term "employed" includes those who worked for pay or profit during the survey reference week. "Unemployed" refers to those who did not have work during that week, but who actively looked for work during the previous four weeks. This population includes those temporarily laid off. "Not in the labor force" includes those who were not designated as either employed or unemployed during the reference week. These definitions were adopted for the NSF SESTAT surveys from Bureau of Labor Statistics definitions. See http://stats.bls.gov/cps/cps_faq.htm.
 Unless otherwise noted, all differences stated in this report are significant with a 95-percent confidence interval. Significant tests were performed with a generalized variance function (GVF) model, using parameters available for SDR data sets or for SESTAT data sets for specific years.
 Ninety-four percent confidence level.
 Unlike the SESTAT population (which includes those with a bachelor's or a master's degree as their highest degree), the population sampled for the SDR is restricted to those who earned doctorates from U.S. institutions. However, the differences between SDR results and those derived from the doctoral component of SESTAT are not large enough to affect the comparisons presented in this report.
 Source: National Science Board, Science and Engineering Indicators: 2000 (Arlington, VA: National Science Foundation, NSB-00-1, 2000), pp. 3-2.