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Chapter 3. Science and Engineering Labor Force

Scope of the S&E Workforce

Measures of the S&E Workforce

The terms scientist and engineer can include very different sets of workers. This section presents three types of measures that can be used to estimate the size and describe the characteristics of the U.S. S&E labor force.[1] Different categories of measures are better adapted for addressing some questions than others, and not all general population and workforce surveys include questions in each category (table 3-1).


U.S. federal occupation data classify workers by the activities or tasks they primarily perform in their jobs. The Occupational Employment Statistics (OES) survey administered by the Bureau of Labor Statistics (BLS) relies on employers to classify their workers using standard occupational definitions. National Science Foundation (NSF) and Census Bureau occupational data in this chapter come from surveys in which individuals (NSF) or members of their household (Census Bureau) supplied information about job titles and work activities. With this information, jobs can be coded into standard occupational categories. Differences between employer- and employee-provided information can affect the content of occupational data.

NSF has developed a widely used set of occupational categories that it calls S&E occupations. These occupations are generally associated with a bachelor's degree level of knowledge and education in S&E fields. A second category of occupations, S&E-related occupations, also requires some S&E knowledge or training, but not necessarily as a required credential for being hired or at the bachelor's degree level. Examples of such occupations are S&E technicians or managers of the S&E enterprise who may supervise people working in S&E occupations. Other occupations, although classified as non-S&E, may include individuals who use their 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.

Other general terms, including science, technology, engineering, or 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.

In this chapter, the narrow classification of S&E occupations is sometimes expanded to include S&E technicians, computer programmers, and S&E managers. This broader grouping is referred to here as STEM occupations.


The pool of S&E workers can also be identified by educational credentials. Individuals who possess an S&E degree, whose highest degree is in S&E, or whose most recent degree is in S&E may be qualified to hold jobs that require S&E knowledge and skills and may seek such jobs if they do not currently hold them. However, a focus on people with relevant educational credentials also includes individuals who hold jobs that are not generally identified with S&E and who are not likely to seek S&E jobs in the future. Furthermore, workers with degrees in S&E may not have kept up to date with the fields in which they were trained, may lack interest in working in jobs that require skills associated with S&E education, or may have advanced in their careers to a point where other skills have become more important.

S&E Technical Expertise

The S&E workforce may also be defined by the expertise required to perform a job or the extent to which job requirements are related to formal training in S&E. Many people, including some outside S&E occupations or without S&E degrees, report that their jobs require at least a bachelor's degree level of technical expertise in engineering, computer sciences, mathematics, the natural sciences, or social sciences, which we refer to in this report as S&E technical expertise. Unlike defining the S&E workforce by occupational groupings or educational credentials, defining it by the use of technical knowledge, skills, or expertise involves assessing the content and characteristics of individual jobs. However, it also involves asking survey respondents to make a complex judgment about their jobs and apply a criterion that they are likely to interpret differently.[2] A recent survey provides clues to how college-educated Americans understand job-related technical expertise. (See sidebar, "Technical Expertise on the Job.")

Size of the S&E Workforce

In the most recent estimates, the U.S. S&E workforce (defined by occupation) totaled between 4.8 million and 6.4. million people (table 3-3). Those in S&E occupations who also had bachelor's degrees were estimated at between 4.8 million (Census Bureau 2009) and 4.9 million (NSF, National Center for Science and Engineering Statistics [NCSES], Scientists and Engineers Statistical Data System [SESTAT]).[3] SESTAT's 2008 estimates for individuals with an S&E degree at the bachelor's level or higher (17.2 million) or whose highest degree was in S&E (12.6 million) were substantially higher than the number of current workers in S&E occupations. Many of those whose highest degree is in S&E reported that their job, although not in an occupation classified as S&E, was closely (2.2 million) or somewhat (2.1 million) related to their highest degree. Counting these people, along with those in S&E occupations, as part of the S&E workforce increases the SESTAT S&E workforce estimate from 4.9 million to 9.1 million, an 84% increase.

The 2003 SESTAT surveys provide a recent estimate for a different assessment of S&E work—whether workers believe their jobs require technical expertise at the bachelor's degree level or higher in S&E fields. According to these surveys, 12.9 million bachelor's degree holders reported that their jobs required at least this level of expertise in one or more S&E fields. This contrasts with 2003 SESTAT estimates of 4.8 million workers in S&E occupations and 11.9 million whose highest degree was in an S&E field.

Growth of the S&E Workforce

However defined, the S&E workforce has for decades grown faster than the total workforce. Defined by occupation, growth in the S&E workforce can be examined over nearly seven decades using Census Bureau data. The number of workers in S&E occupations grew from about 182,000 in 1950 to 5.4 million in 2009. This represents an average annual growth rate of 5.9%, much greater than the 1.2% growth rate for the total workforce older than age 18 during this period. The somewhat broader category of S&T occupations grew from 205,000 to 6.6 million (a 6.1% growth rate) (figure 3-1).

In each decade, the growth rate of S&E occupations exceeded that of the total workforce (figure 3-2). During the 1960s, 1980s, and 1990s, the difference in growth rates was very large (about 3 times the rate for the total labor force). It was smallest during the slower growth period of the 1970s. Between 2000 and 2007, the ratio of the S&E growth rate to the overall workforce was 1.6, which was comparable to the 1970s. The economic downturn at the end of this decade resulted in almost no overall workforce growth for the decade as a whole, well below the 1.4% growth rate for the S&E workforce for the same period. While both the total and S&E employment experienced smaller growth rates in the 2000s compared to the 1990s, the trend of higher growth rates in S&E occupations relative to other jobs continues, even through the recent economic downturn. S&E occupational employment has grown from 2.6% of the workforce in 1983 to 4.8% of all employment in 2010 (figure 3-3).

Recent OES employment estimates for workers in S&E occupations indicate that the S&E workforce has remained steady while the total workforce has declined. The OES estimate was 5.5 million in May 2010, compared to 5.6 million in May 2007. The total workforce declined from 134 million to 127 million in this time frame. The broader STEM aggregate (including technicians, S&E managers, etc.) also remained relatively steady at 7.4 million in May 2010, compared to 7.6 million in May 2007. OES projections for 2008 to 2018 are that S&E occupations will grow at a faster rate than the total workforce. (See sidebar, "Projected Growth of Employment in S&E Occupations.")

Between 1980 and 2000, although the number of S&E degree holders in the workforce grew more than the number of people working in S&E occupations, degree production in all broad categories of S&E fields rose at a slower rate than employment in S&E jobs (figure 3-4). (See chapter 2 for a fuller discussion of S&E degrees.) During this period, S&E employment grew from 2.1 million to 4.8 million (4.2% average annual growth), while annual S&E degree production increased from 526,000 to 676,000 (1.5% average annual growth). Except for mathematics, computer sciences, and the social sciences, the growth rate for advanced degrees was higher than for bachelor's degrees.

This growth in the S&E labor force was possible largely because of three factors: (1) increases in U.S. S&E degrees earned by both native and foreign-born students who entered the labor force, (2) temporary and permanent migration to the United States of those with foreign S&E educations, and (3) the relatively small proportion of scientists and engineers retiring from the S&E labor force. Many have expressed concerns about the effects of changes in any or all of these factors on the future of the U.S. S&E labor force (see NRC 2010 and NSB 2003).

Educational Distribution of Those in S&E Occupations

Workers in S&E occupations have undergone more formal education than the general workforce (figure 3-5). Nonetheless, these occupations include workers with a range of educational qualifications. For all workers in S&E occupations except postsecondary teachers,[4] data from the 2009 U.S. Census Bureau's American Community Survey (ACS) indicate that slightly more than one-quarter had not earned a bachelor's degree. For an additional 44%, a bachelor's was their highest degree. The proportion of workers with advanced degrees was about equal to that of those without a bachelor's degree. Only about 6% of all S&E workers (except postsecondary teachers) had doctorates.

Technical issues related to occupational classification may inflate the estimated size of the nonbaccalaureate S&E workforce. Even so, these data indicate that many individuals enter the S&E workforce with marketable technical skills from technical or vocational schools (with or without earned associate's degrees) or college courses, and many 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 exams, not formal degrees, to judge skills. (See "Who Performs R&D?" and the discussion in chapter 2.)

Among individuals with at least a bachelor's degree who work in S&E occupations, a large proportion (88%) have at least one S&E degree, and 75% have S&E degrees only (table 3-4). S&E workers who have both S&E and non-S&E degrees very likely earned their first bachelor's degree in S&E, even if their highest degree was not in an S&E field. Among workers in S&E occupations, the most common degrees are in engineering (38%) and computer sciences and mathematics (22%) (figure 3-6).

S&E Degree Holders in Non-S&E Occupations

S&E degree holders work in all manner of jobs. For example, they work in S&E-related jobs such as health occupations (1.4 million workers) or in S&E managerial positions (367,000 workers), but they also hold non-S&E jobs such as college and precollege teachers in non-S&E areas (655,000 workers) or work in social services occupations (634,000 workers) (appendix table 3-2).

In 2008, 6.3 million workers whose highest degree was in an S&E field did not work in an S&E occupation. Some 1.3 million worked in S&E-related occupations, while 5.1 million worked in non-S&E jobs. The largest category of non-S&E jobs was management and management-related occupations, with 1.5 million workers, followed by sales and marketing occupations, with 882,000 workers (appendix table 3-2).

Only about 38% of college graduates whose highest degree is in an S&E field work in S&E occupations (figure 3-7). The proportion is higher for those with more advanced degrees. The overall proportion varies substantially by field, ranging from engineering (64%) at the top, followed closely by computer sciences and mathematics (56%) and physical sciences (54%). Although a smaller percentage (30%) of biological/agricultural/environmental life sciences degree holders work in S&E occupations, an additional 26% of persons with degrees in these fields work in S&E-related occupations (appendix table 3-2). Individuals with social science degrees (14%) are least likely to work in S&E occupations. This pattern of field differences generally characterizes individuals whose highest degree is either a bachelor's or a master's. At the doctoral level, the size of these field differences shrinks substantially.

By field, holders of degrees in computer sciences and mathematics and engineering most often work in the broad occupation group in which they were trained (53% and 50%, respectively). S&E doctorate holders more often work in an S&E occupation similar to their doctoral field (55%) compared with individuals whose highest degree is an S&E bachelor's (23%) (appendix table 3-3).

Relationships Between Jobs and Degrees

Most individuals with S&E highest degrees who work in S&E-related or non-S&E occupations do not see themselves as working entirely outside their field of degree. Rather, most indicate that their jobs are either closely (34%) or somewhat (33%) related to their degree field (table 3-5). Among those in managerial and management-related occupations, for example, 33% characterize their jobs as closely related and 42% as somewhat related. More than half (52%) of workers in sales and marketing say their S&E degrees are closely or somewhat related to their jobs. Among S&E precollege teachers whose highest degree is in S&E, 72% say their jobs are closely related to their degrees.

Workers with more advanced S&E education more often do work that is at least somewhat related to their field of degree. Up to 5 years after receiving their degrees, 96% of S&E doctorate holders say that they have jobs closely or somewhat related to their degree field, compared with 92% of master's degree holders and 75% of bachelor's degree holders (figure 3-8). Even when the fit between an individual's job and degree is assessed using the stricter criterion of closely related, the data indicate that many S&E bachelor's degree holders who received their degree up to 5 years earlier are working in jobs that use skills developed during their college training (figure 3-9). In the natural sciences and engineering fields (i.e., S&E degree fields excluding the social sciences), half or more characterized their jobs as closely related to their field of degree: 58% in engineering, 57% in physical sciences, 60% in computer/mathematical sciences, and 46% in biological, agricultural, and environmental life sciences. The comparable figure for social science graduates (30%) was substantially lower.

The stronger relationship between S&E jobs and S&E degrees at higher degree levels holds at all 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. However, for each group, the relationship between job and field of degree becomes weaker over time. There are many reasons for this decline: individuals may change their career interests, gain skills in different areas, take on general management responsibilities, forget some of their original college training, or even find that some of their original training has become obsolete. Against this background, the career-cycle decline in the relevance of an S&E degree appears modest.

The loose relationship among jobs, degrees, and individuals' perceptions of the expertise they need to do their work can be seen in figures 3-10 and 3-11. In figure 3-10, the intersecting area shows individuals whose highest degree is in S&E who are also working in S&E occupations. Less than one-third of SESTAT respondents fall in this area—the rest have one or the other attribute but not both. Figure 3-11 compares three groups of individuals who hold at least a bachelor's degree: those whose highest degree is in S&E and who say their job is at least somewhat related to their degree, those who say they need at least a bachelor's degree level of S&E expertise to perform their job, and those in S&E occupations. In 2008, about 13 million Americans had one or more of these characteristics.[5] Yet these three characteristics are not strongly associated with each other:

  • Only 27% had all three characteristics, and 43% had only one.
  • Even among those in S&E occupations, only about 71% also had S&E degrees, had jobs at least somewhat related to S&E, and believed they needed at least a bachelor's degree level of S&E expertise.
  • Among the people who claimed they needed the technical expertise associated with an S&E bachelor's degree for their job, more than 40% said either that their job was unrelated to their actual degree or that their highest degree was not in S&E.


[1] The standard definition of the term labor force includes the population that is employed or not working but seeking work (unemployed); other individuals are not considered in the labor force. When data refer only to employed persons, the term workforce is used. For data on unemployment rates by occupation, calculations assume that unemployed individuals are seeking further employment in their most recent occupation.
[2] Despite the limitations of this subjective measure, variations among occupations in the proportions of workers who say they need this level of S&E technical expertise accord with common sense. For example, among doctoral level postsecondary teachers of physics, 99.7% said they needed at least a bachelor's degree level of knowledge in engineering, computer sciences, mathematics, or the natural sciences, compared with 5% among doctoral level postsecondary teachers of English. Likewise, among the small numbers of S&E bachelor's degree holders whose occupation is secretary/receptionist/typist, fewer than one in six reported that their job needed bachelor's level S&E expertise of any kind.
[3] Estimates of the size of the S&E workforce vary across the example surveys because of differences in the scope of the data collection (SESTAT surveys collect data from individuals with bachelor's degrees and above only); because of the survey respondent (SESTAT surveys collect data from individuals, OES collects data from establishments, and ACS collects data from households); or because of the level of detail collected on an occupation, which aids in coding. All of these differences can affect the estimates.
[4] Many comparisons using Census Bureau data on occupations are limited to looking at all S&E occupations except postsecondary teachers because the Census Bureau aggregates all postsecondary teachers into one occupation code. Only NSF surveys of scientists and engineers and some BLS surveys collect data on postsecondary teachers by field.
[5] SESTAT/National Survey of College Graduates (NSCG) 2003 and 2008 estimates for the data displayed in figure 3-11 are not comparable. The 2003 estimates include a full complement of respondents to the 2003 NSCG, many of whom report that their jobs require S&E expertise, even though they lack degrees in S&E fields. SESTAT 2008 continues to gather data from S&E degree holders identified in the NSCG, but does not include individuals who are not either in S&E occupations or holders of S&E degrees. Thus, SESTAT 2003 data, although less current, are in some ways better suited for analyzing the relationships among occupations, degrees, and subjective assessments of job requirements. Relevant 2003 data were reported in Science and Engineering Indicators 2010. Because of the limitations of the 2008 SESTAT data, 3-3 uses 2003 estimates.