Overall, a greater proportion of doctoral scientists and engineers working part time wanted full-time work than did part-time workers whose highest degree were bachelor's or master's degrees (table 5). For example, for scientists and engineers aged 35-49 working part time, 28 percent of those with doctorates wanted full-time work, compared with 15 percent with master's degrees and 12 percent with bachelor's degrees as their highest degree.
The percentage of doctoral scientists and engineers working part time but wanting full-time work ranged from 24-34 percent for age groups up to 59, dropping steadily thereafter to about 10 percent for those aged 70-75 (table 5). Overall, some 9,650 doctoral scientists and engineers, constituting 24 percent of those employed part time, wanted full-time work. For those aged 60-75, there were 1,670 doctoral scientists and engineers, 13 percent of those working part time, who wanted full-time employment.
Doctoral scientists and engineers aged 65-75 most frequently stated that retirement or semi-retirement was the reason they were working part time (77 percent), followed by not needing or wanting to work full-time (33 percent). Some 6 percent said that they could not find a suitable full-time job, indicating that older science and engineering doctoral workers were more likely to be employed part time out of choice rather than necessity.
 A related result from a previous study indicates that of the doctoral scientists and engineers aged 63-70 who reported having "retired," some 13.9 and 17.6 percent continued to work part and full time, respectively. For those older than 70, 5.4 percent worked part time and 10.9 percent full time. Source: National Science Board, Science and Engineering Indicators: 2000 (Arlington, VA: National Science Foundation, NSB-00-1, 2000), pp. 3-23. Note that these results are based on SESTAT, not SDR, data on doctoral scientists and engineers.
 Multiple responses allowed; reports based on 9,210 scientists and engineers aged 65-69.