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B
STATISTICS ON GRADUATE EDUCATION OF SCIENTISTS AND ENGINEERS

Michael McGeary
Study Director, Committee on Science,
Engineering, and Public Policy

Contents

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OVERVIEW

About 1,500 institutions of higher learning in the United States have programs leading to degrees in science and engineering. Of those, nearly 300 offer doctoral-degree programs in science and engineering. They also offer master's degrees, and more than 400 nondoctoral academic institutions offer master's-degree programs in science and engineering. In 1992, about 430,000 graduate students were in science and engineering programs; 87% of them were at the 300 doctorate-granting institutions.

In 1992, about 80,000 master's degrees and 25,000 doctoral degrees were earned in science and engineering fields. About one-fourth of the doctorates were awarded in each broad field of science and engineering: physical/mathematical sciences, life sciences, social sciences, and engineering. The median time from the bachelor's degree to the PhD was 9.2 years. More than half of the master's degrees and 90% of the PhDs are awarded by the 150 universities that receive 90% of federal academic R&D funding.

About 5% of all science and engineering doctorate recipients in 1993 (14% of life-sciences PhDs) were supported by federal fellowships and traineeships. Another 61 % (including 78% of physical scientists and 69% of engineers) received external support, primarily research assistantships and teaching assistantships. Many of the research assistantships were funded by federal grants. About one-quarter of the science and engineering doctoral recipients (including one-half the social scientists) were self-supporting (including federally guaranteed loans).

More than one-third more doctorates in science and engineering were awarded in 1993 than in 1983. Seven-tenths of the net increase in doctorate awards went to foreign citizens with temporary visas, and most of the remaining increase was to US women. In 1993, nearly 30% of the doctorates were earned by women, up from about 25% in 1983. In 1992, 5.7% of PhDs were earned by members of underrepresented minorities in 1992, up from 4.1 % in 1983; most of the increase was earned by Hispanics. Foreign citizens with temporary visas greatly increased their share of US doctorates, earning 18.5% in 1983 and 32% in 1993; almost all the net increase was accounted for by citizens of Asian countries. Nearly half of the engineering PhDs went to foreign citizens with temporary visas.

THE GRADUATE STUDENTS

In 1992, the National Science Foundation (NSF) estimated that about 431,600 students were enrolled in graduate science and engineering degree programs (NSF, 1994a:Table 1). Most (87%) were enrolled in doctorate-granting institutions, a proportion that has varied only slightly since the NSF survey began in 1975. Most (67%) were full-time students (this proportion was 72% in doctorate-granting institutions).

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It is not possible to tell which of these graduate students were enrolled in master's degree programs and which in doctoral programs, although many PhD recipients have master's degrees (72% in 1993) (NRC, 1995:Appendix Table A-3).

Table B-1, a comparison of the distribution of science and engineering graduate students among fields by type of institution and enrollment status shows that life-sciences graduate students were somewhat more likely than science and engineering graduate students overall to be at doctorate institutions and to be enrolled full-time. Social sciences and behavioral-science graduate students had the opposite pattern: they were somewhat more likely to be part-time and at master's institutions. Engineering graduate students were slightly more likely to be at doctorate institutions but more likely to be enrolled part-time.

SOURCE: Calculated from Table 1 in NSF, 1994a.

Non-US Citizens

Nearly 110,000 (25.3%) science and engineering graduate students were not US citizens in 1992. About 93,000 of them were enrolled full-time. Their distribution among fields differed from that of US-citizen science and engineering graduate students. Table B-2 shows the distribution of full-time science and engineering graduate students by citizenship and broad field in 1992. Those who were not US citizens were more likely to be studying engineering or the physical sciences and less likely to be in life-science or social/behavioral-sciences programs.

As a result, those who were not US citizens constituted relatively high proportions in some fields—46% of all full-time graduate students in engineering and 39% of those in the physical/mathematic sciences—but low proportions in other fields—27 % of all full-time graduate students in the life sciences and 17% of those in the social/behavioral sciences or psychology.

SOURCE: Calculated from Tables 13 and 14 in NSF, 1994a.

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Female Graduate Students

In 1992, more than 150,000 (35%) science and engineering graduate students were women (up from 25% in 1977). As Table B-3 shows, they were more likely to be enrolled in the life sciences or the social/behavioral sciences and less likely to be in the physical sciences or engineering. In fact, half of all female science and engineering graduate students were in social sciences and psychology programs.

As a result, the majority (54%) of graduate students in the social/behavioral sciences were women, as were 44% of those in the life sciences. Only 15% of engineering graduate students and 27% of those in the natural (physical, environmental, mathematical, and computer) sciences were female.

SOURCE: Calculated from Table 8 in NSF, 1994a.

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Members of Underrepresented Minorities

Fewer than 29,000 (9%) of science and engineering graduate students who were US citizens were members of underrepresented minorities—black, Hispanic, or American Indian. Compared with all US-citizen graduate students, they were much more likely to be studying social/behavioral sciences (53 versus 37%) and substantially less likely to be in the life sciences (13% versus 20%). Members of underrepresented minorities constituted 13% of US citizens in the social/behavioral sciences and about 7% of those in the other broad fields (see Table B-4).

SOURCE: Calculated from Table 2 in NSF, 1994a.

Growth Trends in Full-Time Graduate Enrollment Since 1982

In 1992, there were nearly 291,000 full-time science and engineering graduate students, 30.6% more than in 1982. The growth by field is presented in the first column of Table B-5. Much of the net growth came from foreign citizens; as overall enrollment was increasing by almost 2% a year, foreign enrollment was growing by more than 5% a year (NSB, 1993:50). The second and third columns of Table B-5 compare the increases in full-time science and engineering graduate students who were foreign citizens with those who were US citizens in 1982-1992, by field.

Enrollment increases were also driven by the increased participation of women—3 % a year, compared with 1 % among men, during the 1980s. There were absolute decreases in the number of male graduate students in the life, environmental, and social sciences and psychology (NSB, 1993:53).

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SOURCES: Calculated from Tables 13 and 14 in NSF, 1994a for 1992; Table B-5 in NSF,
1993a for 1982.

Growth in First-Year and Beyond-First-Year Enrollments, 1982-1992

The NSF survey of graduate students and postdoctorates in science and engineering fields began to collect information on the number of first-year full-time enrollments in 1982. The data indicate that first-year enrollments increased at a lower rate than total full-time enrollments until about 1989, after which they increased more rapidly for several years. During 1982-1992, first-year enrollments increased by 17% and beyond-first-year enrollments by 37% (Table B-6). It is difficult to interpret those data. Are the recent large increases in first-year enrollments the result of reports in the middle to late 1980s of impending shortfalls in the number of PhDs or the tendency of more college graduates to go to graduate school when economic conditions are poor? Also, how much of the higher rate of growth among beyond-first-year graduate students until recently was simply the manifestation of the steadily increasing degree requirements among science and engineering PhDs, and how much was due to graduate students' deliberately delaying completion of their degrees as short-term responses to poor job-market prospects?

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SOURCES: Calculated from Tables B-34 and B-35 in NSF, 1992a for 1982; Tables B-24 and
B-25 in NSF, 1993a for 1983-1994; unpublished NSF Tables for 1985-1992.

Sources and Mechanisms of Financial Support

In 1992, science and engineering graduate students were supported in a number of ways by a variety of sources. For each full-time student, the NSF survey asks for the ''major" (i.e., largest) source of support (e.g., federal, institutional, and self) and the type (e.g., fellowship, and/or research assistantship). Table B-7 shows that the sources of support vary considerably from field to field. Although on the average 20% of full-time science and engineering graduate students received their major support from a federal source, this was the largest source of support for 32% of graduate students in biology and nearly 36% of graduate students in the physical sciences. Only 7% of graduate students in the social or behavioral sciences and 10% of those in the mathematical sciences were supported primarily by federal funds. Nearly twothirds of mathematical scientists and half of those in the physical sciences received their major support from their institutions (mostly in the form of research and teaching assistantships), but institutional funds were also an important source of graduate support in the other disciplines—between 32 and 45%. "Own funds" (including, however, federally guaranteed loans) were the major source of support for large fractions of graduate students in some fields—46% of those in computer science and 40% of those in the social and behavioral sciences—but for relatively few in physics, astronomy, and chemistry (6%) or the biological sciences (13%). Only a few percent received foreign support (although those completing the

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survey might not always have known whether those funding their own way—thus classified as self-supporting—were receiving foreign support). Finally, about 7% overall were receiving support from industry and domestic sources other than federal and institutional. About 11% of students in engineering and agricultural science were receiving such support.

SOURCE: Calculated from Table 11 in NSF, 1994a.

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The pattern of sources of support has not changed much over the last 10 years, as seen in Table B-8; federal, institutional, and other US sources of support were up by several percentage points each, offsetting relative declines in foreign and own sources of support.

SOURCES: Calculated from Table C-18 in NSFa, 1992 for 1982; and Table 11 in NSF, 1994a for 1992.

The sources of federal support for full-time science and engineering graduate students also varied by field (see Table B-9), although the pattern has not changed since 1982 (compare NSF, 1992: Table C-18).

National Institutes of Health (NIH) NIH is the primary source of support for nearly 70% of federally supported graduate students in the biological sciences and also accounts for one-third (34%) of federally funded graduate students in psychology. Overall, NIH is the major source of support for more than one-fourth of the federally supported science and engineering graduate students. Other Health and Human Services (DHHS) agencies pick up a few percent more.

United States Department of Agriculture (USDA) The majority (55%) of federally supported agricultural-science students are funded by USDA. USDA is the primary supporter of few other graduate students (a little more than 5% of federally funded students).

Department of Defense (DoD) Nearly half (45%) of those with major federal support in the computer sciences and more than one-fourth of those in the mathematical sciences are funded by DoD. Overall, DoD is the major source of support for 15% of federally funded graduate students.

National Science Foundation (NSF) Almost one-third of the graduate students in physical sciences who receive their major support from federal sources are funded by NSF. Overall, NSF supports more than a one-fifth of the federally funded graduate students.

Other Other federal agencies are the major source of support for 29% of federally supported graduate students, especially in the social (44%) and environmental (44%) sciences. The only fields that do not receive much support from other federal agencies are the biological (8%) and the computer (14%) sciences.

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SOURCE: Calculated from Table 11 in NSF, 1994a.

As for the mechanisms of support (including nonfederal), the latest detailed data by field are for 1991 (Table B-10).

Fellowships Fellowships are awarded to individual graduate students on the basis of merit. Table B-10 shows that about 10% of the 259,000 full-time science and engineering graduate students were supported by fellowships in 1991, and fellowship support was spread fairly evenly across the disciplines (about one-fourth of the fellowships were federally funded).

Traineeships Traineeship programs are competitively awarded to universities, which select the graduate students to support. About 4% of science and engineering graduate students were trainees, most of them in the biological sciences. (About 60% of the trainees were federally supported; 30% were institutionally funded.)

Research Assistantships About 30% of full-time science and engineering graduate students were supported as research associates on research grants awarded to faculty supervisors. The proportion varied by field. Graduate students in the some of the physical sciences and the life sciences were more likely to be research associates; those in the mathematical sciences and

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social and behavioral sciences were less likely. (About half the research assistants were supported by federal funds and one-third by institutional funds.)

Teaching Assistantships More than one-fifth (23 %) of graduate students were supported primarily as teaching assistants. Graduate students in mathematics and in the physical sciences were especially likely to be teaching assistants; those in engineering and agricultural sciences were less likely than average to have teaching assistantships.

Other Support "Other support" includes loans, personal funds, and tuition payments by industry and government agencies. It accounts for more than a third (33 %) of graduate students. It was especially important in some fields; about half those in computer science, psychology, and social sciences were supported other than by fellowships, traineeships, and research or teaching assistantships. Graduate students in biology or the physical sciences were less likely to rely on other types of support.

SOURCE: Calculated from Tables C-19 and C-20 in NSF, 1993a.

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Science and Engineering Graduate Students in Master's-Granting Institutions

In 1992, nearly 57,000 science and engineering graduate students were in institutions whose highest degree is the master's. Most of them (65%) were enrolled part-time. Table B- 11 gives their distribution and enrollment status by field and compares them with graduate students at doctorate-granting institutions. The table indicates that graduate students in master's degree institutions were much more likely to be in the social sciences and psychology and much less likely to be in the life sciences. In fact, 26% of all graduate students in the social sciences and psychology were in master's-degree institutions, compared with 11% of the remaining science and engineering graduate students.

SOURCE: Calculated from Tables 20 and 21 in NSF, 1994a.

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THE INSTITUTIONS

In 1991, there were 3,611 institutions of higher education in the United States; they enrolled 14 million students and granted 1.9 million degrees, of which about one-fourth (470,000) were in science and engineering fields (NSB, 1993:38). The Carnegie Foundation for the Advancement of Teaching has classified those institutions into categories according to the size of their bachelor's-degree and graduate programs, amount of research funding, and—for liberal-arts colleges—selectivity of admissions. Table B-12 shows how many institutions were in each category in 1991.

SOURCE: Calculated from Appendix Table 2-6 in NSB, 1993.

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Although comprehensive and liberal-arts institutions were the majority of institutions granting science and engineering bachelor's and master's degrees, the research and doctorate institutions accounted for large fractions of the degrees granted: 54% of all science and engineering bachelor's degrees and 53% of the master's degrees. Degree production is especially concentrated at the doctoral level (see Table B-13): nearly two-thirds of the science and engineering PhDs awarded in 1991 came from the 71 Research I universities, four-fifths from the 105 Research I and II universities; and nine-tenths from the 153 Research I and II and Doctorate I universities. The same set of 153 universities also receives 90% of all academic R&D funding (NSB, 1993:40; Appendix Table 2-5).

SOURCE: Calculated from Appendix Table 2-6 in NSB, 1993.

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The 105 Research I and II universities produce nearly 80% of the science and engineering doctorates awarded each year (see Table B-14). This concentration of PhD production differs some by broad field, although the 71 Research I institutions accounted for at least the majority of PhDs granted in each.

SOURCE: Calculated from Appendix Table 2-5 in NSB, 1993.

There was substantial growth in the number of institutions with graduate degree programs since 1961 (see Table B-15). The number of institutions granting doctorates doubled between 1961 and 1991; the number of master's-degree institutions more than doubled.

SOURCE: Calculated from Appendix Table 5-1 in NSB, 1985 for 1961-1981; and Appendix
Table 2-6 in NSB, 1993 for 1991.

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SCIENCE AND ENGINEERING MASTER'S DEGREES

Master's Degrees in Science and Engineering

The number of master's degrees awarded in science and engineering has grown every year since 1966 except in the 1979-1981 period (Table 1 in NSF, 1994b). In 1991, over 78,000 science and engineering master's degrees were awarded, up from 41,000 in 1966. Science and engineering master's degrees were 29% of all master's degrees awarded in 1966, a percentage that declined to less than 21 in 1976, increased to 25% in 1987, and fell again to 23% in 1991.

According to Table B-16, about one-third of science and engineering master's degrees are awarded in the social and behavioral sciences, three-tenths in engineering, one-fourth in the natural sciences, and one-tenth in the life sciences (NSF, 1994b). (Compared with 1966, the social/behavioral sciences increased their share by almost 9 percentage points, gaining 5 points from the life. sciences, 3 from engineering, and 1 from the natural sciences.)

SOURCE: Calculated from Table 1 in NSF, 1994b.

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Women

Women earned 13.3% of the science and engineering master's degrees in 1966, a percentage that increased steadily to nearly 36% in 1991 (see Table B-17). This varied by field.

The number of science and engineering master's degrees per 1,000 24-year-old women in the US population increased from 4 in 1966 to 15 in 1991 (NSF, 1994b:Table 57). Meanwhile, the number going to men went from more than 30 per 1000 in 1969-1970 to 26 in 1991 (after reaching a high of 32 in 1970 and a low of 21 in the early 1980s). Overall, in 1991, 21 master's degrees in science and engineering were awarded for every 1000 24-year-olds in the US population, up from 15 in 1966.

SOURCE: Calculated from Table 18 in NSF, 1994b.

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Underrepresented Minorities

NSF has collected information on the race, ethnicity, and citizenship of master's degree recipients biennially since 1977. Table B-18 shows that the proportion of science and engineering master's degrees awarded to members of underrepresented minorities (i.e., blacks, Hispanics, and American Indians) has increased slowly in the natural sciences and engineering, offset by declines in psychology and the social sciences, fields that traditionally have registered the largest shares of underrepresented minorities.

SOURCE: Calculated from Table 4 in NSF, 1994c.

Non-US Citizens

Non-US citizens with temporary visas received almost 20% of the science and engineering master's degrees in 1991, almost double their share in 1977 (see Table B-19). Most

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were in physical or mathematical science and engineering programs, where they constituted about 30% of all master's-degree students. They were relatively unlikely to be in social-science or psychology programs.

SOURCE: Calculated from Table 4 in NSF, 1994g.

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SCIENCE AND ENGINEERING DOCTORAL DEGREES

Doctorates in Science and Engineering

The number of science and engineering PhDs awarded annually tripled between 1958 and 1968 to about 18,000. Between 1968 and 1974, the number leveled off or fell in various fields, although the aggregate number peaked in 1971-1973 at nearly 19,400 per year, and fell to fewer than 18,000 per year by 1977, where it remained through 1981. Table B-20 shows the numbers of science and engineering PhDs awarded during 1983-1993 period.

SOURCE: Calculated from Table 1 in NSF, 1994b.

In 1982, the number of science and engineering doctorates awarded annually rose above 18,000 for the first time since 1976. The growth rate was still low—about 2% per year—until 1988, when the increase was more than 5% over 1987. The number increased by around 3 % per year from 1988 through 1993. Table B-21 shows the increases from 1988 to 1993 by field

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SOURCE: Calculated from Table 1 in NSF, 1994f.

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Women

The number of women awarded science and engineering PhDs increased from 4,624 in 1983 to 7,537 in 1993, or 63.0%. As a result, the proportion of PhD awards to women increased from 25.1% in 1983 to 29.9% in 1993. They varied from field to field (see Table B22).

SOURCE: Calculated from Tables 1 and 2 in NSF, 1994b.

Women earning science and engineering PhDs were concentrated in particular fields. In 1993, nearly half (45%) were in the social and behavioral sciences, and 30% were in the life sciences (see Table B-23). The concentration in social and behavioral sciences was reduced over the previous 10 years, however, as more awards to women were made in the physical and mathematical sciences and engineering. Overall, the shift was 4.5 percentage points (to nearly 18%). The number of women receiving PhDs in the physical and mathematical sciences more than doubled from 1983 to 1993 (from 617 to 1,344). The number in engineering quadrupled (from 124 to 521), but fewer than 7% of women PhDs were in engineering.

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SOURCE: Calculated from Table 2 in NSF, 1994f.

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The percentage of science and engineering doctorates awarded to members of underrepresented minorities—American Indians, blacks, and Hispanics—has been very low and has increased slowly (see Table B-24). In fact, the percentage of doctorates received by black citizens declined during the last half of the 1980s.

SOURCE: Calculated from Table 3 in NSF, 1994f.

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Non-US Citizens

In 1993, more than 8,000 science and engineering PhDs went to foreign citizens with temporary visas—nearly one-third of all the doctorates awarded by US universities (see Table B-25). Only 18.5% of PhDs awarded in 1983 went to foreign citizen with temporary visas. In 1993, they received just under half of the new doctorates in engineering, up from 42% 10 years earlier. They were awarded more than one-third (36%) of the PhDs in the physical and mathematical sciences and more than one-fourth (28%) of those in the life sciences.

SOURCE: Calculated from Table 4 in NSF, 1994f.

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The number of non-US citizens with temporary visas increased 138% over a decade—from 3,400 in 1983 to 8,087 in 1993 (Table B-26). That increase was greater in the physical and mathematical sciences and in the life sciences. The rate of growth was lower than average in the social and behavioral sciences.

SOURCE: Calculated from Table 4 in NSF, 1994f.

Table B-27 shows the distribution of foreign citizens with temporary visas, by field. In 1993, roughly one-third were in engineering, and another one-third were in the physical/mathematical sciences. Around 15-20% were in each of the life sciences and the social sciences. Compared with 1983, temporary-visa holders moved away from the social sciences (by about 4.5 percentage points) and into the physical/mathematical sciences (by about 2 points) and the life sciences (by about 2.5 points).

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SOURCE: Calculated from Table 4 in NSF, 1994f.

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The country of origin of temporary-visa holders shifted during the 1980s (see Table B28). Citizens from eastern Asia increased their share of science and engineering PhDs awarded to temporary-visa holders from one-fourth to more than a half. Nearly all this increase was accounted for by students from the People's Republic of China, who increased their share from near zero in 1982 to 22% of all the science and engineering PhDs earned by temporary-visa holders in 1992.

SOURCE: Calculated from Table 5 in NSF, 1994f.

The annual reports of the Survey of Earned Doctorates conducted by the National Research Council for NSF have documented a substantial increase since 1970 in the time it has taken to obtain a PhD, whether measured in years since the bachelor's degree or in years registered in graduate school. According to these reports, which calculate the median time-to-degree (TTD) of all those obtaining PhDs each year, the figure has increased by about 30% over the last 20 years.

According to the latest report of the Survey of Earned Doctorates, total TTD (years from bachelor's degree to doctorate), or TTTD, went up by 29.6% from 1967 to 1993, from 8.1 to 10.5 years (Table B-29). The trend in registered time-to-degree (RTTD) was similar—31.5% (from 5.4 to 7.1 years). However, 1967 was near the postwar total-TTD low of 8 years reached in 1970. TTTD increased for decades (from 7 years in 1920 to 9 in 1962), fell during the 1960s to the low of 8 years in 1970, and then resumed its upward trend after 1970 (Bowen and Rudenstine, 1992:Figure 6.3).

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Those figures are for all PhDs in all fields, including humanities, education, and the professional (which have had the highest TTDs historically). The patterns vary widely by field, even within the sciences and engineering. Engineering and physical sciences have always had shorter than average completion times; social sciences, longer.

The increase in TTD has slowed considerably since about 1987, even though the recession of the early 1990s might have increased the incentive to stay in school a year or two longer.

SOURCE: Calculated from Table 6 in NRC, 1995.

In conducting the research for their recent book In Pursuit of the PhD, Bowen and Rudenstine (1992:113-119), noticed that TTD figures were lower for their sample of 10 schools. They consulted demographers who suggested a different method for determining TTD that should be more accurate. The method used by the Office of Scientific and Engineering

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Personnel (OSEP) and others determines the median number of TTD years for all those receiving their doctorates in a particular year. The demographers pointed out that this permits a bias if the cohorts entering graduate school are increasing or decreasing in size over time. Each entering class of PhD candidates has some fast finishers and some slow finishers. In a period such as the late 1950s and 1960s, when the number entering PhD programs was growing every year, the proportion of fast finishers showing up for their degrees a few years later increased and made the decreases in TTD larger than they would have been if cohorts had been steady. Similarly, when cohort sizes decrease, as they did in 1974-1984, the proportion of fast finishers getting their degrees a few years later goes down, increasing the apparent TTD. More recently, enrollments have gone up again, and that accounts for at least part of the decrease in TTD medians in the past several years.

Bowen and Rudenstine corrected for that bias by calculating average TTD of entering cohort, rather than graduating cohort. They asked, how long on the average, did it take those entering a PhD program (or getting their bachelor's degrees in year X to get their doctorates? They found that use of the entering-cohort method gave an increase in TTD of about 10% over the preceding 15-20 years, not 30%. They admitted that any lengthening in the already-long TTD is a serious problem but said that its magnitude and newness had been exaggerated.

A study of TTD by staff of OSEP reviewed the literature on the causes of increasing TTD (Tuckman, et al., 1990). They found that earlier studies had looked at sociological, demographic, economic, and institutional factors, although few had looked at them all and undertaken a causal analysis. They developed a model of TTD with five vectors of variables: family background characteristics, individual abilities and interests, tuition and financial aid, institutional environment and policies, and economic and social forces. They tested the model in 11 fields using data from the Survey of Earned Doctorates and found a variety of factors that affected registered time-to-degree (RTTD) or total time-to-degree (TTTD), including the availability and form of student support, labor-market conditions, sociodemographic characteristics of the doctorate recipients, and characteristics of the undergraduate and graduate institutions. Yet no factor or set of factors consistently explained the general upward trend in TTD. That might be because TTD is poorly measured (the study was based on the graduating, rather than the entering, cohort), or because the data are inadequate. They are aggregate data, and some measure the variables of interest only indirectly; other variables, such as increasing complexity of subject matter or the incentive for faculty to keep students longer as cheap labor on research projects, are not measured at all.

As for negative consequences, the following have been mentioned (Tuckman, et al., 1990):

· The increasing time spent in graduate school increases the time it takes for the supply of PhDs to respond to shifts in market demand, and that has both social and individual costs (if demand goes up, there are not enough qualified people; if it falls, highly capable people cannot be employed in their field of training).

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· Increasing TTD will discourage some highly qualified candidates from staying in science (perhaps some of the most qualified students, who can more easily find attractive alternatives).

· Delayed start of career reduces the total years of productivity for society and the return on investment for the individual.

Bowen and Rudenstine (1992) also studied the effects of financial support in some detail in their 10-school sample. They found that it mattered. Students who received financial aid had much higher completion rates and shorter TTD than students who relied on their own resources. In the sciences, the form of the aid had an effect on completion and TTD; research assistantships had the best effect, fellowships a close second, and teaching assistantships the worst effect. They also found that the NSF fellowship program had been very successful in reducing median TTD (4.9 years versus 5.6 years for those who were not NSF fellows in an eight-university group). Interpreting such findings is problematic, however. Did the NSF fellows finish earlier because of the fellowship form of support itself or because they were selected through a rigorous process that selected more-motivated students?

In conclusion, both RTTD and TTTD have been increasing for a long time, with the exception of the 1960s. Presumably, the increases are caused in part by the increasing complexity of knowledge and techniques to be mastered in doctorate programs and in part by less-desirable or less-excusable reasons (e.g., an increase in tuition costs and a decrease in federal aid, which force students to work more during graduate school, or a desire of faculty to keep students working on research projects). They are also caused in part by the increasing participation of women and minority-group members, who generally have longer TTDs.

According to Bowen and Rudenstine, having outside aid does improve completion and TTD rates. The form of the aid—fellowships, research assistantships, or teaching assistantships—might have little independent effect.

Source of Support

The Survey of Earned Doctorates (SED) administered yearly by OSEP for NSF asks new PhDs to list their primary source of support during graduate school. The data for 1993 are displayed in Table B-30. It should be noted, however, that the nonresponse rate to this question was 34%, for unknown reasons (it was 23% in 1991, and 30% in 1992). It also should be noted that federally funded research assistantships are listed with other research assistantships under ''university" because students often do not know the source of support for their research assistantships. Federal loans are listed under "personal." "Other" includes national fellowships, employer funds, and support from foreign governments, state governments, and other nonspecified sources. The "life sciences" include "health science" PhDs as well as the biological and agricultural scientists listed in the other tables in this appendix.

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A brief analysis of the table shows that a relatively large percentage of the PhD recipients in social sciences are self-supporting—nearly half, compared with 10-15% of those in the physical sciences and engineering and a fifth of those in the life sciences.

PhDs in the life sciences receive the most direct federal support, probably resulting from the large fellowship and traineeship programs of the National Institutes of Health.

Most PhDs in the physical sciences and engineering, and to a lesser extent the life sciences, receive their primary support from their universities. That includes federally funded research assistantships, as well as other research and teaching assistantships.

SOURCE: Calculated from Table 11 in NRC, 1995.

POSTDOCTORATE EMPLOYMENT PLANS

According to the SED, among new science and engineering PhDs who had definite postgraduation plans, the percentage planning to work in academe (college or university) was 48% in the early 1960s (NRC, 1978:Table 30). That figure increased to 57.0% in 1970 before falling steadily to 44.1% in 1980 (NSF, 1993b:Table 15) and 40.4% in 1993 (NSF, 1994f:Table 7). Meanwhile, the proportion of new science and engineering PhDs going to business and industry grew from about 22% in the 1960s to 26.5% in 1970 and 36.2% in 1993.

Note that Table B-31 does not include those with definite plans for postdoctoral study in the United States, almost all at universities. These numbered 2,789 in 1970, 3,571 in 1980, 4,676 in 1990, and 5,739 in 1993 (NSF, 1993b:Table 15, 1994f:Table 7).

It also should be noted that the percentage of science and engineering PhDs who had definite plans at the time of the SED survey fell from 76.6% in 1970 to 72.0% in 1980, 64.0% in 1990, and 60.1% in 1993 (NSF, 1993b:Table 15, 1994f:Table 7).

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SOURCE: Calculated from Table 5 in NSF, 1993b.

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POSTDOCTORAL STUDY TRENDS

SOURCE: Calculated from Appendix Table A-3 in NRC, 1993.

SOURCE: Calculated from Appendix Table A-3 in NRC, 1993.

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