This chapter examines the postdoctoral appointment (postdoc) as a component of the career of doctoral scientists and engineers. Discussed here will be the total number of postdocs held, the postdoctoral status of the population in 1995, characteristics of those on postdocs in 1995, reasons for holding postdocs, and the relevance of the postdoc to the principal job held in 1995.
Number of Postdocs
- Overall, 34 percent of science and engineering doctorates had held at least one postdoc and 9 percent had held multiple postdocs since award of the doctorate. Ph.D.s in the biological sciences were most likely to have held at least one postdoc (62 percent). Roughly half of those in chemistry and physics/astronomy also had held at least one postdoc. Least likely were doctorates in computer sciences and social sciences (10 and 12 percent, respectively). Biological sciences Ph.D.s were also most likely to have held multiple postdocs (20 percent) (see Table 25).
- The proportion having held at least one postdoc was inversely related to the number of years since the Ph.D. was granted, ranging from 27 percent for those more than 25 years since degree award to 40 percent for those with 5 years or less since doctorate.
- By field, the trend toward holding a postdoc was also evident. Doctorates in physics/astronomy showed the largest increase in the proportion who held a postdoc, from 36 percent of the Ph.D.s with more than 25 years since the degree to 72 percent of those 5 years or less since the doctorate. Of biological sciences Ph.D.s with more than 25 years since the doctorate, 45 percent held a postdoc; of those 5 years or less since the doctorate, 71 percent held at least one. Only doctorates in social and health sciences showed a decline in the percentage with at least one postdoc from the cohort more than 25 years since degree to the most recent 5 year cohort.
Reasons for Holding Postdocs
- Of those who had held postdocs at some time in their careers, "additional training in Ph.D. field" was most frequently cited as the primary reason for taking the first postdoc (47 percent), followed by "work with a specific person or place" (21 percent). This distribution was similar for those with only one postdoc and those who held more than one (see Table 26).
- By field among those who had ever held a postdoc, additional training was the primary reason cited most frequently (with the exception of doctorates in earth/atmospheric/marine sciences whose primary reason was most often work with a specific person).
- A higher than average proportion of doctorates in engineering and agricultural/ environmental sciences cited employment not available as the reason for their first postdoc (25 and 26 percent, respectively, compared with 11 percent for doctorates overall).
- For those doctorates with multiple postdocs, the primary reasons for the second postdoc were still most likely to be additional training and work with a specific person, but the proportions were closer, 35 and 25 percent, respectively. For those holding multiple postdocs, "other employment not available" was cited as the primary reason for the second postdoc by 14 percent (compared with 9 percent citing this reason for their first postdoc).
The next several comments in this section pertain to those science and engineering doctorates who were on postdocs in April 1995 (see Table 28 ).
- In 1995, 4 percent of science and engineering doctorates were on postdocs, with doctorates in biological sciences having the highest proportion (10 percent). The lowest proportion was in social sciences, less than 1 percent (see Table 27).
- Predictably, doctorates earning their degrees within the last 5 years had the highest proportion on postdocs, 19 percent. This proportion dropped to 2 percent for doctorates from 6 to 10 years out, and to less than 1 percent for those more than 10 years out.
- By field within the most recent 5-year cohort, 44 percent of biological sciences Ph.D.s and 39 percent of physics/astronomy Ph.D.s were on postdocs.
- Of those on postdocs in 1995, 85 percent were from the most recent 5-year cohort and 58 percent were less than 35 years old.
- In 1995, those on postdocs were more likely to be Asian (27 percent) and non-U.S. citizens (29 percent) than the most recent 5-year cohort of science and engineering doctorates overall (22 percent Asian and 24 percent non-U.S. citizens). The most recent 5-year cohort is used as the comparison group because most of the 1995 postdoctoral appointees were from this cohort (see above). Approximately one-third of both the postdoctoral appointees and the most recent cohort overall were female.
- Most postdoctoral appointees in 1995 were working in educational institutions (55 percent), followed by government (33 percent), business/industry (7 percent), and other sectors (5 percent). This distribution by sector was similar for postdoctoral appointees with doctorates in chemistry, physics/astronomy, and biological sciences. The exceptions were psychology, where 20 percent reported "other" sector, and engineering, with 12 percent in business/industry.
- Generally, most of those on postdocs in 1995 received health benefits (84 percent) but not pension benefits (37 percent). However, the proportions receiving these benefits varied by field. Ninety percent of physics/astronomy doctorates on postdocs received health benefits and 50 percent received pension benefits. On the other hand, only 57 percent of psychology doctorates received health benefits and 18 percent received pension benefits.
Relevance of Postdoc to 1995 Principal Job
Those individuals who had held a postdoc but were not on a postdoc appointment in April 1995 were asked to rate the relevance of their most recent postdoc to the work on their 1995 principal job. Table 29 shows the proportion who said the aspects of their most recent postdoc were "a great deal" or "somewhat" relevant to their job.
- "General approach or problem solving skills" was rated relevant by 90 percent of the doctorates. "Subject matter knowledge or expertise" was relevant for 85 percent, followed by "contacts established with colleagues in your field" at 80 percent and "use of specific skills or techniques" at 73 percent. "Use of specialized equipment" was considered relevant by the smallest proportion, 58 percent.
- Even for doctorates graduating more than 25 years earlier and presumably furthest removed from the postdoc experience, all aspects were considered relevant to the 1995 job by at least 50 percent.
- Even though a relatively small proportion of psychology doctorates ever held postdocs (25 percent), they rated all aspects of the postdoc (except use of equipment) relevant as or more frequently than doctorates in any of the other selected fields.
 A postdoctoral appointment was defined on the survey as "a temporary position awarded in academe, industry, or government primarily for gaining additional education and training in research."
 Because the proportion or the number of doctorates taking postdocs was quite low for certain fields, data for these fields are not shown separately in Table 28 or Table 29, but are included in the total column. These fields are computer, mathematical, earth/atmospheric/marine, health, and social sciences.