Appendix A: Technical Notes
General Information
- Racial/Ethnic Information
- Information About Persons With Disabilities
- Primary Sources
General Information 
The data in this report come from many sources, including surveys conducted by Federal and State agencies and by professional associations. The data reflect many methods of collection, such as universe
surveys, sample surveys, and compilations of administrative records. Users should take great care when comparing data from different sources. Data often will not be strictly comparable due to differences in definitions, survey procedures, phrasing
of questions, etc.
Survey accuracy is determined by the joint effects of "sampling" and "nonsampling" errors. Sampling errors arise because estimates based on a sample will differ from the figures that would have been
obtained if a complete census had been taken.
All surveys, whether universe or sample, are also subject to nonsampling errors, which can arise from design, reporting, and processing errors as well as errors due to faulty response or nonresponse. These
nonsampling errors include respondent-based events such as: some respondents interpreting questions differently from other respondents; respondents making estimates rather than giving actual data; and respondents unable or unwilling to provide
complete, correct information. Errors can also arise during the processing of responses, such as faulty imputation or reweighting to adjust for nonresponse, recording and keying errors, etc.
Racial/Ethnic Information
Data collection and reporting of the race/ethnicity of individuals pose several additional problems. First, both the naming of population subgroups and their definitions have often changed over time. Since
this report draws on data from many sources, different terminology may have been used to obtain the various statistics presented here. Efforts have been made to maintain consistency throughout this text, but in some data reporting it has been
necessary to use distinct terminology that does not match other compilations.
Second, many of the groups of particular interest are quite small, so that it is difficult to measure them accurately without universe surveys. In some instances sample surveys may not have been of
sufficient scope to permit calculation of reliable racial/ethnic population estimates, so that results are not shown for all groups. In addition, the reader is cautioned that it is easy to overlook or minimize the heterogeneity within subgroups when
only a single statistic is reported for the total racial/ethnic group.
Information About Persons With Disabilities
The data on persons with disabilities in science and engineering are seriously limited for several reasons. First, there have been differing operational definitions of "disability" that include a wide range
of physical and mental conditions. Different sets of data have used different definitions and thus are not totally comparable. The Americans with Disabilities Act of 1990 (ADA) encouraged progress toward standard definitions. Under the ADA, an
individual is considered to have a disability if the person has a physical or mental impairment that substantially limits one or more of the major life activities; has a record of such impairment; or is regarded as having such an impairment. The ADA
also contains definitions of specific disabilities. (See appendix table 1-1.)
Second, data about disabilities are frequently not included in comprehensive institutional records (e.g., in registrars' records in institutions of higher education). If included at all in institutional
records, such information is likely to be kept only in confidential files at an office responsible for providing special services to students. Institutions are unlikely to have information regarding any persons with disabilities who have not
requested special services. In the case of elementary/secondary school programs receiving funds to provide special education, however, counts for the entire student population identified as having special needs are centrally available.
The third limitation on information on persons with disabilities gathered from surveys is that it often is obtained from self-reported responses. Typically, respondents are asked if they have a disability
and to specify what kind of disability it is. Resulting data, therefore, reflect individual perceptions, not objective measures.
Finally, data on persons with disabilities are often derived from sample surveys whose main purpose is to derive estimates for a full population. Deriving estimates for any phenomenon that is applicable
to a small proportion of the total is particularly difficult, especially when the sampling procedures do not have a way to "oversample" cases providing the characteristic of interest. Since persons with disabilities constitute a relatively small
portion of the population, sample sizes may not be sufficiently large to permit calculation of reliable estimates.
An example in which these factors come together can be seen in the attempt to provide estimates of the proportion of the undergraduate student population with disabilities. Self-reported data from the
undergraduate student population, queried on a survey to ascertain patterns of student financial aid, suggest that about 10 percent of the undergraduate population report having some disability; estimates from population surveys of higher education
institutions, in contrast, place the estimate much lower, between 1 and 5 percent. Whether this discrepancy is the result of self-perception, incomplete reporting, nonevident disabilities, or differing definitions is difficult to ascertain.
Therefore, although there is considerable information available on persons with disabilities and their status in the educational system and in the science and engineering workforce, it is often not
possible to compare the numbers of persons with disabilities from different sources.
Primary Sources
1. Current Population Reports, P70-33: Americans With Disabilities: 1991-92
Contact
Current Population Reports
Bureau of the Census
U.S. Department of Commerce
Washington, DC 20233
Tel: (301) 763-8300
This report presents data on the disability status of the noninstitutionalized population of the United States. The source of the data is a combined sample from the 1990 and 1991 panels of the Survey of
Income and Program Participation. A supplement containing an extensive set of questions about disability status was included as part of the sixth wave of the 1990 panel and the third wave of the 1991 panel. Both of these waves were fielded between
October 1991 and January 1992. The total sample size for this study was approximately 30,000 interviewed households. Estimation procedures were used to inflate weighted sample results to independent estimates of the civilian noninstitutional
population of the United States.
Twelve questions were used to determine disability status for this study. These concerned the presence of limiting conditions such as difficulty with sensory and physical functional activities; difficulty
with activities of daily living; the existence of specific conditions such as dyslexia, developmental disabilities, or other mental or emotional conditions; and the presence of a physical, mental, or other health condition limiting the kind or amount
of work or housework that the person can do. For children, there were additional questions such as whether the children had received therapy or diagnostic services, had limitations in their ability to do regular schoolwork, or had a long-lasting
condition that limited their ability to undertake activities such as walking and running. A person was considered to have a disability if the individual was identified affirmatively by any of the 12 category questions.
2. Survey of Public Attitudes Toward and Understanding of Science and Technology and Biomedical Sciences in the United States: 1992 (Public Attitudes Survey)
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel: (703) 306-1777
Fax: (703) 306-0508
Surveys of public attitudes toward science and technology, supported by the National Science Foundation for the past two decades, were designed to collect data on the public's interest in, knowledge of,
sources of information for, attentiveness toward, and attitudes regarding science, technology, health, and biomedical information and issues.
The 1992 Survey of Public Attitudes consisted of telephone interviews with 2,001 adults aged 18 and over in a national probability sample. It contained a core set of questions that have been asked since
1979, as well as new topical questions. Data were collected by gender, level of education, extent of science and math education, age, race/ethnicity, and other background demographic characteristics.
In 1992, the National Institutes of Health joined with the National Science Foundation to sponsor a similar national study of public understanding of biomedical concepts. A total of 3,111 telephone
interviews were conducted using a national sample stratified by race/ethnicity. Black and Hispanic college graduates were oversampled using the same probability techniques employed with the base sample to allow meaningful comparisons of college
graduates of these populations.
3. National Assessment of Educational Progress, 1969 to 1992
Contact
National Center for Education Statistics
U.S. Department of Education
555 New Jersey Avenue, NW
Washington, DC 20208-5653
Tel: (202) 219-1761
Fax: (202) 219-1751
The National Assessment of Educational Progress (NAEP) is sponsored by the National Center for Education Statistics (NCES) and has been conducted since 1983 by the Educational Testing Service. The overall
goal of the project is to determine the Nation's progress in education. Accordingly, NAEP encompasses a series of national sample surveys designed to assess students in 10 subject areas such as reading, mathematics, science, writing, history, etc.
Begun in 1969, NAEP was conducted annually through 1980; since 1980 the project has been conducted biennially. NAEP has surveyed the educational accomplishments of 9-, 13-, and 17-year-old students (and in recent years, those in grades 4, 8, and 12
as well). Over the years NAEP has undergone extensive changes both in survey methodology and in the assessment areas covered, to reflect changing informational needs and possible changes in education achievement.
NAEP used a complex multistage stratified sample of schools, selected to ensure adequate representation of schools with high enrollment of blacks and Hispanics. Approximately 8,500 students at each
age/grade level were tested in mathematics and another 8,500 in science. Overall response rates (taking into account both school and student response rates) for the grade levels examined in 1990 ranged from 75 to 82 percent.
The assessment excluded students with limited English proficiency and students receiving special education services who were mainstreamed less than 50 percent of the time.
4. National Education Longitudinal Study of 1988
Contact
National Center for Education Statistics
U.S. Department of Education
555 New Jersey Avenue, NW
Washington, DC 20208-5651
Tel: (202) 219-1777
Fax: (202) 219-1728
The National Education Longitudinal Study of 1988 (NELS:88) was conducted by the National Center for Education Statistics as part of a long-term national education project that also included both the National
Longitudinal Study of the High School Class of 1972 and the High School and Beyond Study. The project's goal was to monitor the educational, vocational, and personal development of students as they move through the grades. NELS:88 began with a
baseline assessment of academic achievement and school experience of eighth grade students in 1988; they were followed up on a biennial basis to observe how the eighth grade experience affected later educational and occupational attainment.
The base year study obtained participation from 1,057 public and private schools and encompassed 24,599 students. The instruments utilized in the base year study included student questionnaires combined
with cognitive tests, as well as questionnaires for parents, teachers, and school administrators. As a complement to NELS:88, teacher transcript data were collected to examine science and mathematics teachers' characteristics, their qualifications,
and their preparation for teaching.
The first follow-up survey was conducted in 1990, surveying the initial 8th grade cohort as 10th graders; the second follow-up was performed in 1992 for the cohort as seniors. For the follow-ups, a
dropout questionnaire was added to the existing instruments to obtain information about the characteristics of dropouts from the eighth grade cohorts and their return to school.
Readers of this report should note several factors about the NELS:88 coverage of certain subgroups: The school universe chosen was restricted to regular public and private schools with eighth grade
students. A supplementary sample of Hispanic and Asian/Pacific Islander students (and their parents and teachers) was included, but schools operated by the Bureau of Indian Affairs were excluded. Special education schools for persons with
disabilities, area vocational schools that did not enroll students directly, and schools for dependents of U.S. personnel overseas were also excluded. Students identified as having mental disability, physical or emotional problems, or a language
barrier were also excluded from the sample.
5. American College Testing Program
Contact
The American College Testing Program
2201 North Dodge Street
P.O. Box 168
Iowa City, IA 52243
Tel: (319) 337-1510
The American College Testing (ACT) Assessment is taken by college-bound high school students who request that the results be sent to designated colleges and scholarship boards. The ACT is designed to measure
educational development in the areas of English, mathematics, social studies, and natural sciences. The test results are used in part to help predict how well students might perform in college. In 1993, approximately 875,000 students took the ACT
examinations.
ACT standard scores are reported for each subject area on a scale from 1 to 36. A composite score is obtained by taking the simple average of the four standard scores and is an indication of a student's
overall academic development across the four subject areas.
Since the 1984-85 school year, national norms have been based on the test scores of all students taking the test. These norms are based on the most recent ACT scores available from students scheduled to
graduate in the spring of the year.
It should be noted that college-bound students who take the ACT Assessment are not, in some respects, representative of college-bound students nationally. First, students who live in the Midwest, South,
and Rocky Mountains and Plains regions are overrepresented among ACT-tested students compared with college-bound students nationally. Second, ACT-tested students tend to enroll in public colleges and universities more frequently than do
college-bound students nationally.
6. Scholastic Aptitude Test (SAT)
Contact
College Entrance Examination Board
Educational Testing Service
Princeton, NJ 08541
(609) 771-7600
The Admissions Testing Program of the College Board comprises a number of college admissions tests, including the Scholastic Aptitude Test (SAT). The SAT is taken by students who need the results to apply to
a particular college or university or scholarship board. High school students participate in the testing program as sophomores, juniors, or seniors-some more than once during these 3 years. If they have taken the tests more than once, only the most
recent scores are tabulated.
The SAT reports subscores in the areas of mathematics and verbal ability. Students may also elect to take Achievement Tests in any of 18 subject areas; these exams are generally taken by students who are
applying to the more competitive schools. In 1993, approximately 1 million students took the SAT examination, and close to 200,000 took at least one Achievement Test.
Students may also take Advanced Placement exams in any of 29 subject areas; high scores on these exams may qualify them for advanced placement in their college courses in these areas. In 1993, over 400,000
students took at least one Advanced Placement exam.
The SAT results are not representative of high school students or college-bound students nationally since the sample is self-selected. In addition, public colleges in a number of States require that
students applying for admission submit ACT scores (see above) rather than SAT scores; thus, the proportion of students taking the SAT in some States is very low.
7. The 1992 National Norms Study of The Cooperative Institutional Research Program
Contact
Higher Education Research Institute
Graduate School of Education
University of California
320 Moore Hall
Los Angeles, CA 90024-1521
Tel: (310) 825-1925
Fax: (310) 206-2228
This series, initiated in 1966, provides national normative data on the characteristics of students attending American colleges and universities as first-time, full-time first-year students. The series is a
project of the Cooperative Institutional Research Program (CIRP), a national longitudinal study of the American higher education system sponsored by the American Council on Education and the Graduate School of Education at the University of
California, Los Angeles.
Since 1972, the CIRP freshman surveys have been conducted by the Higher Education Research Institute at the University of California, Los Angeles. The 1992 CIRP freshman norms are based on the responses of
213,630 students at 404 of the Nation's 2- and 4-year colleges and universities, statistically adjusted to reflect the responses of the 1.7 million first-time, full-time students entering college as freshmen in fall 1992.
The 1992 Student Information Form is a student self-report questionnaire composed of 39 multiple choice items. The questionnaire obtains data from students in eight areas: academic skills and
preparation; demographic trends; high school activities and experiences; educational and career plans; majors and careers; attitudes; student values; and means of financing education.
The CIRP National Norms Study sample is derived from students attending institutions that volunteered to participate in the study. Therefore, it is not a random sample of the U.S. population of higher
education institutions and students. As a result, survey findings may not present trends in the Nation as a whole.
8. The Integrated Postsecondary Education Data System Survey: Fall Enrollment, Completions and Institutional Characteristics
Contact
National Center for Education Statistics
U.S. Department of Education
555 New Jersey Avenue, NW
Washington, DC 20208-5652
Tel: (202) 219-1373
Fax: (202) 219-1679
The Integrated Postsecondary Education Data System (IPEDS) began in 1986 as a supplement to and replacement for the Higher Education General Information Survey (HEGIS) which began in 1966. HEGIS was an annual
survey of institutions listed in the current NCES Education Directory, Colleges and Universities; IPEDS surveys all postsecondary institutions, including universities and colleges and the institutions that offer technical and vocational education.
The higher education portion is a census of accredited 2- and 4-year colleges, while technical and vocational schools are surveyed on a sample basis.
IPEDS consists of several integrated components that obtain information on types of institutions where postsecondary education is available, student participants, programs offered and completed, and the
human and financial resources involved in the delivery of postsecondary education. The components of IPEDS include surveys of institutional characteristics; fall enrollment of students, including their age and residence; fall enrollment in
occupationally specific programs; completions; finance; staff; salaries of full-time instructional faculty; and academic libraries.
The IPEDS Institutional Characteristics survey provides the basis for the universe of institutions reported in the Education Directory of Colleges and Universities. The universe includes institutions that
met certain accreditation criteria and offered at least a 1-year program of college-level studies leading toward a degree. Each fall, institutions listed in the previous year's directory are asked to update information on the characteristics of their
school.
The IPEDS Completions Survey replaces and extends the HEGIS Degrees and Other Formal Awards Conferred Survey. The Completions Survey is administered to a census of institutions offering degrees at the
bachelor's level and above, all 2-year institutions, and a sample of less than 2-year institutions.
The IPEDS Fall Enrollment Survey replaces and extends the previous HEGIS Fall Enrollment and Compliance Report of Institutions of Higher Education.
Imputations were developed for institutions that provided incomplete racial/ethnic data. Some of these institutions had reported total degrees awarded but not racial/ethnic data. In these cases, NCES
imputed data on the basis of an earlier response for each institution, if available. The percentage of imputed data for racial/ethnic categories in 1991 ranged from 2.4 percent to 14.9 percent for bachelor's degrees, and from 2.4 percent to 7.1
percent for master's degrees.
Other institutions reported totals that were larger or smaller than the sum of the racial/ethnic components, or reported racial/ethnic data as unknown. In these cases, NCES distributed the difference among
the racial/ethnic groups for that institution.
9. Survey of Earned Doctorates
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel (703) 306-1774
FAX: (703) 306-0510
The Survey of Earned Doctorates (SED) has been conducted annually since 1957, under contract by the National Research Council of the National Academy of Sciences, for the National Science Foundation, the U.S.
Department of Education, the National Endowment for the Humanities, the National Institutes of Health, and the U.S. Department of Agriculture. This is a census survey of all recipients of research doctoral degrees such as Ph.D. or D.Sc.; it excludes
the recipients of first-professional degrees such as J.D. or M.D. Therefore, SED data are restricted to research doctorates.
Data for the SED are collected directly from individual doctorate recipients. The recipients are asked to provide information on the field and specialty of their degree, as well as their personal
educational history, selected demographic data, and information on their postgraduate work and study plans. Approximately 95 percent of the annual cohort of doctorate recipients respond to the questionnaire, which is distributed through the
cooperation of the graduate deans at institutions awarding doctorates.
Partial data from public sources, such as field of study, are added to the file for nonrespondents. However, there are no imputations for nonresponse for data not available elsewhere, such as
race/ethnicity information. The data for a given year include all doctorates awarded in the 12-month period ending on June 30 of that year.
10. Curriculum Assessment Service Database: Estimates of Student Curricular Activities From a National Survey of Colleges and Universities (Transcript Study)
Contact
Institute for Research on Higher Education
University of Pennsylvania
4200 Pine Street, 5A
Philadelphia, PA 19104-4090
Tel: (215) 898-5897
Fax: (215) 898-9876
The data base for this study contains both student course enrollment (transcript) data and demographic information for baccalaureate recipients. The study was developed to provide policy makers and
researchers with a national data base that would allow them to examine and assess the program choices of baccalaureate degree recipients.
The data for this study were drawn from a stratified random sample of U.S. institutions (including schools in Puerto Rico) that granted bachelor's degrees in the liberal arts and sciences in spring 1991.
The sample was stratified according to three variables: private or State control; institutional type based on four Carnegie Commission classes (Comprehensive, Doctoral, Liberal Arts, and Research); and East, Middle, and West regions.
From the 1,360 colleges and universities identified as candidates for inclusion in the sample, a sample of 100 institutions was drawn. A total of 42,007 transcripts from the sample schools were examined.
Eighty-one institutions submitted transcripts for the data base study.
11. Survey of Graduate Students and Postdoctorates in Science and Engineering: 1992
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel: (703) 306-1774
Fax: (703) 306-0510
This annual survey collects data from all institutions offering graduate programs in any science, engineering, or health field. Data are collected at the academic department level. Available information
includes: full-time graduate students by source and mechanism of support, with data on women and first-year students enrolled full time; part-time graduate students by sex; and citizenship and racial/ethnic background of all graduate students. In
addition, detailed data on postdoctorates are available by source of support, sex, and citizenship, with separate data on those holding first-professional doctorates in the health fields; there is also summary information on other doctorate
nonfaculty research personnel.
In fall 1992, the latest survey cycle for which final data are available, the survey universe included approximately 10,800 departments at 608 institutions of higher education, including 333 doctorate- and
275 master's-granting institutions. Separate data were obtained from 119 specialized entities such as medical and dental schools, schools of public health, and other organizational units, bringing the total number of responding entities to 727.
Coverage included all departments in 62 science, engineering, and health fields: 39 science fields (4 physical, 4 environmental, mathematical, computer, agricultural, 17 biological, psychology, and 10 social), 14 engineering fields, and 9 health
fields.
12. The National Postsecondary Student Aid Study, "Undergraduate Financing of Postsecondary Education," 1989-90
Contact
National Center for Education Statistics
U.S. Department of Education
555 New Jersey Avenue, NW
Washington, DC 20208-5652
Tel: (202) 219-1839
Fax: (202) 219-1736
The National Postsecondary Student Aid Study (NPSAS) was established by NCES to collect information concerning financial aid allocated to students enrolled in U.S. postsecondary institutions. After a national
field test in 1985-86, NPSAS was first administered in the fall of the 1986-87 academic year. NCES conducted a second cycle of NPSAS for the 1989-90 school year. This second cycle also contained enhancements to the methodology used in the 1987
cycle.
The 1990 in-school sample involved about 70,000 students selected from registrar lists of enrollees at approximately 1,200 postsecondary institutions. The sample included students who did and did not
receive financial aid. Student information such as field of study, educational level, and attendance status (part-time or full-time) was obtained from registrar records. Types and amounts of financial aid and family financial characteristics were
abstracted from school financial aid records. Also, approximately 26,000 parents of students were sampled to compile data concerning family composition and parental financial characteristics.
Biennial follow-up data collections are expected. Students enrolled in postsecondary education for the first time in 1990 will serve as the base for the longitudinal component of NPSAS.
13. Higher Education Survey, Surveys on Undergraduate Education in Sociology, Physics, Geology, 1991; Undergraduate Education in Electrical, Mechanical, and Civil Engineering, 1994; Technical Education in 2-Year Institutions,
1994
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel: (703) 306-1774
Fax: (703) 306-0510
The Higher Education Surveys (HES) system was established to conduct brief surveys of higher education institutions on topics of interest to Federal policymakers and the education community. The system is
sponsored by the National Science Foundation, the U.S. Department of Education, and the National Endowment for the Humanities.
HES questionnaires typically request a limited amount of readily accessible data from a subsample of institutions in the HES panel, which is a nationally representative sample of approximately 1,100
institutions representing approximately 3,200 colleges and universities in the United States. Each institution in the panel appoints a HES campus representative who serves as the survey coordinator. The campus representative facilitates data
collection by identifying the appropriate respondent for each survey and distributing the questionnaire to that person.
14. Public Use Microdata Samples of the Decennial Census: 1980 and 1990
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel: (703) 306-1776
Fax: (703) 306-0510
To obtain detailed tabulations of scientists and engineers from the 1980 and 1990 Decennial Census, NSF tabulated data from the Public Use Microdata Samples (PUMS) files of the Bureau of the Census. The 1980
5 percent PUMS contains records of the 1980 Census Long Form responses for approximately 5 percent of the total U.S. population. For 1990 data, tabulations were from a combined file made from the 1990 1 percent PUMS and the 1990 5 percent PUMS with
appropriate reweighting.
The tabulations of scientists and engineers from census data were limited to those with a bachelor's degree who reported a science or engineering occupation and were not working in academia. Unlike other
data sources used in this report, scientists and engineers are identifiable on census data only by self-described occupation and not by field of degree; this eliminates those who have left science or engineering employment. In addition, many active
scientists and engineers are excluded because their occupational responses were too generic to classify them within science and engineering (e.g., manager or college professor).
15. Survey of Doctorate Recipients: 1991
Contact
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
Tel: (703) 306-1776
Fax: (703) 306-0510
The Survey of Doctorate Recipients (SDR) is a longitudinal survey designed to provide demographic and career history information about individuals with doctoral degrees. The survey is conducted for the
National Science Foundation and other Federal agencies under contract by the National Research Council of the National Academy of Sciences. The 1991 survey, the 10th in a biennial series, reflects a number of improvements made by the National
Science Foundation. The SDR is a survey of individuals under the age of 76 who hold doctorates in science and engineering from U.S. institutions. The 1991 population differs from prior surveys in the series, which followed a cohort of doctorate
recipients for 42 years. Several other improvements introduced into the 1991 SDR also affect comparability with SDR data published in prior survey years. For example, there was a change in the definition of doctoral scientists and engineers.
Another change made in 1991 was the introduction of more intensive follow-up of mail nonrespondents in order to raise the survey response rate.
Among the variables included in this survey are citizenship, date of birth, disability status, educational history, employment status (unemployed, employed part time, or employed full time), field of
degrees, geographic place of employment, labor force status, occupation, postdoctorate status, primary work activity (e.g., teaching, basic research, etc.), race/ethnicity, salary, sector of employment (academia, industry, government), sex, and years
of professional experience.
The sample size for the 1991 survey was approximately 38,000, with a response rate of 87 percent. The sample was stratified on the basis of field of degree, sex, disability status, racial/ethnic group,
and nativity (i.e., whether born in the United States) in order to provide more reliable data on rare subgroups in the population. The sample frame used to identify these individuals is the Doctorate Records File, maintained by the National Academy
of Sciences. The primary source of information for the frame is the Survey of Earned Doctorates (SED) (discussed separately above). For individuals who received a degree prior to 1957 when the SED started, information was taken from a register of
highly qualified scientists and engineers that the National Academy of Sciences had assembled from a variety of sources.
Since this is a longitudinal survey, recent recipients of research doctorates are added each time the survey is conducted and individuals no longer under age 76 are dropped. Initial data collection in
1991 was by mail. Nonrespondents to the mail questionnaire were followed up, using Computer Assisted Telephone Interviewing techniques. The instrument used in the phone follow-up was modified from the mail instrument to avoid difficulties
encountered in administering some of the questions by phone, especially those (such as field of degree and field of occupation) that require individuals to select from an extensive list of possible responses.
