According to the latest National Science Foundation (NSF) survey of science and engineering graduate departments (unpublished), there were 24,024 science and engineering postdoctoral appointees2in doctorate-granting institutions in the fall of 1992, compared with 14,672 in 1982a 63.7% increase, compared with a 26.7% increase in the number of graduate students. Part of the growth can be assumed to reflect the legitimate need for postdoctoral study and exploration to prepare for the increased complexity of modern science; in biology, chemistry, and physics, for example, postdoctoral study has become the norm. But committee testimony and other anecdotal evidence indicates that many postdoctoral appointees are extending their studies because permanent positions in academic or industrial research are not available.
An important additional factor is the increasing percentage of postdoctoral appointees who are foreign students53% in 1992, compared with 42% in 1985 (NSF, unpublished). More foreign citizens than American citizens have had postdoctoral appointments in US universities since 1991 (Tables C-29 and C-30 in NSF, 1993a).
However, surveys do not determine the extent to which young scientists and engineers take postdoctoral positions because they cannot find regular employment. One measure of the impact of employment-market problems on the growth of the postdoctoral pool would be an increase in the length of postdoctoral time before a permanent position is found or an increase in the percentage of scientists and engineers who take second or third postdoctoral positions. Another indication would be an increasing percentage of scientists and engineers taking postdoctoral appointments at the institutions where they received their doctorates; this would indicate that professors are retaining their former students as RAs when they cannot find regular jobs.
The Survey of Doctorate Recipients can be analyzed to address the question. The comparative analysis of cohorts of scientists and engineers 5-8 years after receipt of their PhDs, done for this report, indicated that the percentage still in postdoctoral positions grew from 2 % in 1977 to 3% in 1989; the increase was greater and smaller in specific fields (see Appendix C, Table C-2).3In 1979, more than 600 (4.9%) of the biologists who received PhDs in 1971-1974 held postdoctoral appointments; in 1989, nearly 1,300 (9.2%) of those with PhDs from 19811984 were in postdoctoral positions. The percentage of each cohort in the faculty tenure system fell from 40% in 1979 to 25% in 1989.
The above changes might partially explain the finding that the percentage of young biologists (aged 36 and younger) who applied to the National Institutes of Health for individual investigator research grants fell by 54% from 1985 to 1993 (NRC, 1994a); clearly, fewer of them were in a position of independent investigator, from which they are permitted to apply for research grants.
2 Both numbers include foreign citizens, but the postdoctoral total includes doctorates in science or engineering from foreign universities. Part of the larger increase in the number of postdoctoral fellows over the last decade, therefore, might be ascribed to a greater propensity of foreign scientists and engineers to immigrate at the postdoctoral than the predoctoral stage, rather than to an increase in the pool of postdoctoral fellows who cannot find a job.
3 The 1989 data from the Survey of Doctorate Recipients are used because, owing to a change in the timing of the survey, the 1991 data on postdoctoral appointments are not comparable.