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. 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.
U.S. federal occupation data classify workers by the activities or tasks they primarily perform in their jobs. The Bureau of Labor Statistics' (BLS's) Occupational Employment Statistics (OES) survey collects data that rely on employers to classify their workers using standard occupational definitions. Census Bureau and National Science Foundation (NSF) occupational data in this chapter come from surveys in which individuals supplied information about job titles and/or work activities. This information enables jobs to be coded into standard occupational categories.
Although there is no standard definition of an S&E occupation,
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 level of knowledge
and education in S&E fields. A second set of occupations,
S&E-related occupations, also require some S&E
knowledge or training, but not necessarily as a required credential
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 salespeople who sell
specialized research equipment to chemists and biologists
and technical writers who edit scientific publications. The
NSF occupational classification of S&E, S&E-related, and
non-S&E occupations appears in table
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 meaning.
In this chapter, the narrow classification of S&E occupations is sometimes expanded to include S&E technicians, computer programmers, S&E managers, and a small number of non-health S&E-related occupations such as actuary and architect. This broader grouping is referred to here as STEM occupations.
The pool of S&E workers could also be identified in terms of 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 choose to seek such jobs if they do not currently hold them. However, a focus on people with relevant educational credentials includes individuals who do not hold jobs that are generally identified with S&E and are not likely to seek them in the future. Workers with degrees in S&E may not have maintained current knowledge of 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 (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.
Defined by occupation, the U.S. S&E workforce totaled
between 4.3 million and 5.8 million people in 2006 (table
The 2003 SESTAT surveys provide the most recent estimate for a different subjective assessment of S&E work—whether 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 in S&E occupations and 11.9 million whose highest degree is in an S&E field.
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 6 decades using Census Bureau data. (For a discussion
of longer periods, see the sidebar "Scientists Since
Babylon.") The number of workers in S&E occupations
grew from about 182,000 in 1950 to 5.5 million in 2007.
This represents an average annual growth rate of 6.2%,
nearly 4 times the 1.6% 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 6.5
In each decade, the growth rate of S&E occupations exceeded
that of the total workforce (figure
Recent OES employment estimates for workers in S&E occupations indicate that the S&E workforce is continuing to grow faster than the total workforce (see table 3A in sidebar "Scientists Since Babylon"). The OES estimate was 5.6 million in May 2007, up 9.9% from the May 2004 total of 5.1 million. This implies an average annual growth rate of 3.2%, about double the 1.6% average annual increase in employment in all occupations. During the same period, the broader STEM aggregate (including technicians, S&E managers, etc.) reached 7.6 million in May 2007 but grew at an average annual rate of 2.2%—slower than S&E occupations because of employment declines for both technicians/programmers and S&E managers. OES projections are that S&E occupations will continue to 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 pace
than employment in S&E jobs (figure
This growth in the S&E labor force was largely made possible by the following 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 education, and (3) the relatively small proportion of scientists and engineers leaving the S&E labor force because they had reached retirement age. 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 NSB 2003).