Chapter 3 | Science and Engineering Labor Force

U.S. S&E Workforce: Definition, Size, and Growth

Because there is no standard definition of S&E workers, this section presents multiple categorizations for measuring the size of the S&E workforce.^​ In general, this section defines the S&E workforce to include people who either work in S&E occupations or hold S&E degrees. Because the application of S&E knowledge and skills is not limited to jobs classified as S&E, the number of workers reporting that their jobs require at least a bachelor’s degree level of knowledge in one or more S&E fields exceeds the number of jobs in the economy with a formal S&E label. Therefore, this section also presents data on the use of S&E technical expertise on the job to provide an estimate of the S&E workforce. The estimated number of scientists and engineers varies based on the criteria applied to define the S&E workforce.

U.S. federal occupation data classify workers by the activities or tasks they primarily perform in their jobs. NSF and Census Bureau occupation data are based on information provided by individuals or household members and classified into categories based on the Standard Occupational Classification (SOC) system (see Appendix Table 3-1).^​ In contrast, the BLS-administered OES survey relies on employers to classify their workers using SOC definitions. Differences between employer- and individual-provided information can affect the content of occupation data.

NSF uses a set of SOC categories that it calls S&E occupations. Very broadly, these occupations include life scientists, computer and mathematical scientists, physical scientists, social scientists, and engineers. NSF also includes postsecondary teachers of these fields in S&E occupations. A second category of occupations, S&E-related occupations, includes health-related occupations, S&E managers, S&E technicians and technologists, architects, actuaries, S&E precollege teachers, and postsecondary teachers in S&E-related fields. The S&E occupations are generally assumed to require at least a bachelor’s degree level of education in an S&E field. The vast majority of S&E-related occupations also require S&E knowledge or training, but an S&E bachelor’s degree may not be a required credential for employment in some of these occupations. Examples include health technicians and computer network managers. Other occupations, although classified as non-S&E occupations, may include individuals who use S&E technical expertise in their work. Examples include technical writers who edit scientific publications and salespeople who sell specialized research equipment to chemists and biologists. The NSF occupational classification of S&E, S&E-related, and non-S&E occupations appears in Table 3-2, along with the NSF educational classification of S&E, S&E-related, and non-S&E degree fields.

Indicative of a knowledge-based economy, the number of individuals who have S&E training or who reported applying S&E technical expertise in their jobs exceeds the number of individuals employed in jobs that are categorized as S&E. Therefore, a relatively narrow definition of the S&E workforce consists of workers in occupations that NSF designates as S&E occupations. In comparison, a much broader definition of an S&E worker, used by NSF’s data on scientists and engineers, includes any individual with a bachelor’s or higher level degree in an S&E or S&E-related field of study or a college graduate with a degree in any field employed in an S&E or S&E-related occupation.

As noted, the S&E workforce may also be defined by the technical expertise or training required to perform a job. Unlike information on occupational categories or educational credentials, information on the use of technical knowledge, skills, or expertise in a person’s job reflects that individual’s subjective opinion about the content and characteristics of the job.^​ The next section provides estimates of the size of the S&E workforce using these three definitions: those who work in S&E occupations, those who hold S&E degrees, and those whose jobs require S&E technical expertise.

Other general terms—including science, technology, engineering, and mathematics (STEM); science and technology (S&T); and science, engineering, and technology (SET)—are often used to designate the part of the labor force that works with S&E. These terms are broadly equivalent and have no standard definition.

When defined by occupation only, the S&E workforce totals approximately 6.7 million people according to the most recent estimates (Table 3-3). Those in S&E occupations who had at least a bachelor’s degree are estimated at between 5.0 million and 6.4 million.^​ By far the largest categories of S&E occupations are in computer and mathematical sciences and in engineering, which together account for about 76% (among college-educated workers) to 85% (among workers of all education levels) of all employed workers in S&E occupations (Figure 3-1). Occupations in life, social, and physical sciences each employ a smaller proportion of S&E workers.

As noted earlier, S&E degree holders greatly outnumber those currently employed in S&E occupations. In 2015, about 23 million college graduates in the United States had a bachelor’s or higher level degree in an S&E field of study (Table 3-3). About three-fourths of these college graduates (17.3 million) attained their highest degree—a bachelor’s, master’s, professional, or doctorate—in an S&E field (in this chapter, these individuals are referred to as S&E highest degree holders). An individual’s highest degree is often an accurate representation of the skills and credentials that one employs in the labor market, which is why the data presented in this chapter by educational attainment are generally provided for highest degree. Overall, across all S&E highest degrees, social sciences and engineering were the most common degree fields (Figure 3-2).^​ The 17.3 million college graduates with an S&E highest degree includes 12.4 million with bachelor’s degrees, 3.7 million with master’s degrees, 1.2 million with doctorates, and 37,000 with professional degrees.

A majority of S&E degree holders (61%) reported that their job was either closely or somewhat related to their field of highest degree (Table 3-3). Because many of these individuals were employed in occupations not categorized as S&E, this suggests that the application of S&E knowledge and skills is widespread across the U.S. economy and not limited to occupations classified as S&E.

The extensive use of S&E expertise in the workplace is also evident from the number of college graduates who indicate that their job requires technical expertise at the bachelor’s degree level in S&E fields. Nearly 19.4 million college graduates, regardless of field of degree or occupation, reported that their jobs required at least this level of technical expertise in one or more S&E fields (Table 3-3); this figure is three times as large as the 6.4 million college graduates employed in S&E occupations.

The S&E workforce has grown faster over time than the overall workforce. According to Census Bureau data, employment in S&E occupations grew from about 1.1 million in 1960 to about 6.7 million in 2015 (Figure 3-3).^​ This represents an average annual growth rate of 3%, compared to a 2% growth rate in total employment during this period. S&E occupational employment as a share of total employment doubled, from about 2% in 1960 to about 4% in 2015. See sidebar Projected Growth of Employment in S&E Occupations for BLS data on occupational projections for the period 2014–24.

Data indicate that trends in S&E employment fared relatively better than overall employment trends during and after the 2007–09 economic downturn. Occupation-based estimates from BLS indicate that the size of the S&E workforce stayed relatively steady between May 2007 (5.6 million) and May 2010 (5.5 million) and then rose to 6.7 million by May 2016. The broader STEM workforce—including S&E technicians and managers—by May 2016 had increased to 8.7 million from 7.6 million in May 2007. The total workforce fell by 7.3 million between May 2007 (134 million) and May 2010 (127 million) and then rose to 140 million by May 2016.

The growth in the number of individuals with S&E degrees in recent years can be examined using NSF survey data on scientists and engineers. The total number of S&E highest degree holders employed in the United States grew from 9.6 million to 13.5 million between 2003 and 2015, reflecting a 2.9% annual average growth rate. Most broad S&E degree fields exhibited growth (Figure 3-4). (See Chapter 2 for a fuller discussion of S&E degrees.)

A number of factors have contributed to the growth in the S&E labor force over time: the rising demand for S&E skills in a global and highly technological economic landscape; increases in U.S. S&E degrees earned by women, racial and ethnic minority groups, and foreign-born individuals; temporary and permanent migration to the United States of those with foreign S&E educations; and the rising number of scientists and engineers who are delaying their retirement. The demographic sections of this chapter provide data on aging and retirement patterns of scientists and engineers as well as on S&E participation by women, racial and ethnic minorities, and foreign-born individuals.

Workers in S&E occupations have undergone more formal training than the general workforce (Figure 3-5). Data from the 2015 ACS indicate that a larger proportion of workers in S&E occupations (75%) (which in the ACS excludes postsecondary teachers) hold a bachelor’s or higher degree than workers in all other occupations (31%).^​ The proportion of workers with advanced degrees beyond the bachelor’s level is 31% in S&E occupations, compared to 11% in all other occupations. About 7% of all S&E workers (again excluding postsecondary teachers) have doctorates.

Compared with the rest of the workforce, very few of those employed in S&E occupations have only a high school degree. However, many individuals enter the S&E workforce with marketable technical skills from technical or vocational schools (with or without an earned associate’s degree) or college courses; some also acquire these skills through workforce experience or on-the-job training. In information technology—and, to some extent, in other occupations—employers frequently use certification examinations, not formal degrees, to judge skills. (See sidebar A Broader Look at the S&E Workforce and the discussion of community college in the Chapter 2 section Institutions Providing S&E Education.)

Formal S&E training is the usual pathway into S&E occupations. According to the 2015 NSCG, the vast majority (83%) of college graduates employed in S&E occupations have at least a bachelor’s degree in an S&E field (Table 3-4). However, the prevalence of a degree in the same broad field as one’s S&E occupation varies across occupational categories. For example, among computer and mathematical scientists, less than one-half (45%) have a bachelor’s or higher level degree in a field of study that is equivalent to the field in which they work, and about one-fifth (21%) have no degree in any S&E or S&E-related field of study. In contrast, 76% of life scientists, 76% of physical scientists, 81% of social scientists, and 81% of engineers have a bachelor’s or higher level degree in their respective broad field. The next section presents data on the proportion of S&E degree holders who are employed in S&E and non-S&E occupational categories.

Using data from the NSCG, which provides information on both degree achievement and occupational employment of scientists and engineers in the United States, this section analyzes the interplay between degree and occupation for individuals who earned a highest degree in an S&E discipline and those who earned a highest degree in a non-S&E discipline.

Although an S&E degree is often necessary to obtain S&E employment, many individuals with S&E degrees pursue careers in non-S&E fields. However, most workers with S&E training who work in non-S&E jobs reported that their work is related to their S&E training, suggesting that the application of S&E skills and expertise extends well beyond jobs formally classified as S&E occupations. (The section S&E Workers in the Economy provides data on R&D activity of scientists and engineers employed in S&E and non-S&E occupations.)

Only about half of those with a highest degree in S&E are employed in an S&E (36%) or S&E-related (15%) occupation; the other 50% are employed in non-S&E occupations. Figure 3-6 shows the occupational distribution of the S&E workforce with S&E, S&E-related, and non-S&E highest degrees. The largest category of non-S&E jobs for these S&E degree holders is management and management-related occupations (2.5 million workers), followed by sales and marketing (1.1 million workers) (the non-S&E category “Other non-S&E occupations” has a larger total of S&E degree holders, however, it includes a wide variety of non-S&E occupations) (Appendix Table 3-3). Other non-S&E occupations with a large number of S&E-trained workers include social services (429,000) and college and precollege teaching in non-S&E areas (404,000). S&E degree holders also work in S&E-related jobs such as health (666,000), S&E management (477,000), S&E technician or technologist (506,000), and precollege teaching in S&E areas (269,000).

Most individuals with a highest degree in S&E but working in non-S&E occupations still see S&E technical expertise as relevant to their jobs. Most indicate that their jobs are either closely (35%) or somewhat (35%) related to their highest degree field (Table 3-5). A distinctive feature of the U.S. workforce is the multiple pathways that S&E workers take from degree to profession. The National Science Board reports that “[S&E] knowledge and skills enable multiple, dynamic pathways to [S&E] and non-[S&E] occupations alike.” (NSB 2015) For example, among S&E degree holders in non-S&E management and management-related occupations, about three-quarters indicate that their jobs are either closely (31%) or somewhat (43%) related to their S&E degree. Among those in social services and related occupations, these numbers are higher (91%); among those in sales and marketing, these numbers are lower (51%).

Unlike individuals with an S&E highest degree, at least half of those whose highest degrees are either in S&E-related or non-S&E fields are employed in their corresponding broad occupational categories (Figure 3-6). For those with an S&E-related highest degree, the largest category of jobs is health occupations (3.7 million); for those with a non-S&E highest degree, the largest category of jobs is non-S&E management and management-related occupations (1.0 million) (Appendix Table 3-3). Significant numbers of individuals with a non-S&E highest degree work in computer and information sciences (731,000), health-related occupations (532,000), and precollege teaching in S&E areas (526,000) or as lawyers or judges (594,000).

The pattern of a large proportion of individuals with a highest degree in S&E being employed in areas other than S&E occupations has been robust over time. Data from 1993 indicate that 36% of all scientists and engineers with S&E highest degrees were employed in S&E occupations, and the rest held positions in areas other than S&E. The comparable proportion in 2015 was also 36% (Figure 3-6).

The proportion of S&E highest degree holders who go on to work in S&E occupations varies substantially by S&E degree fields and level of degree. Overall, this proportion is heavily influenced by individuals with social sciences degrees, who are the least likely to work in S&E occupations (13%); these individuals work primarily in non-S&E occupations (79%) (Figure 3-7) such as non-S&E management and management-related occupations, sales and marketing, and social services and related occupations including clergy, counselors, and social workers. In contrast, at least half of individuals with a highest degree in computer and mathematical sciences (58%), physical sciences (49%), or engineering (58%) reported working in S&E occupations. This general pattern between study field of degrees and occupations is similar at the bachelor’s and master’s degree levels but not at the doctoral level (Figure 3-8), where S&E doctorate holders most often work in an S&E occupation similar to their doctoral field.

Whereas Figure 3-8 shows the proportion of S&E degree holders employed in S&E occupations, Figure 3-9 shows what proportions of S&E degree holders reported that their work is related (closely or somewhat) to their S&E degree. Workers with more advanced S&E training were more likely than those with only bachelor’s degrees to work in a job related to their degree field. Regardless of degree level, most degree holders in life sciences (76%), physical sciences (79%), computer and mathematical sciences (89%), and engineering (90%) considered their jobs to be related to their degree field. The corresponding percentage of social scientists was 68%.

The pattern of a stronger relationship between S&E jobs and S&E degrees among master’s degree or doctorate holders compared with bachelor’s degree holders is robust across career stages, as seen in comparisons among groups of bachelor’s, master’s, and doctoral degree holders at comparable numbers of years since receiving their degrees (Figure 3-9). However, at each degree level, the percentage of S&E degree holders employed in jobs related to their field of highest degree declines as the number of years since degree increases. This suggests that the relationship between job and field of highest degree becomes weaker over time, particularly toward the later career stages. Possible reasons for this decline include changes in career interests, development of skills in different areas, promotion to general management positions, or realization that some of the original training has become obsolete. Despite these potential factors, the career-cycle decline in the relevance of an S&E degree appears modest.