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Appendix A: Technical Notes

Data presented in Doctorate Recipients from U.S. Universities: 2011 were collected by the Survey of Earned Doctorates (SED). The survey is sponsored by six federal agencies: the National Science Foundation (NSF), National Institutes of Health (NIH), U.S. Department of Education (USED), U.S. Department of Agriculture (USDA), National Endowment for the Humanities (NEH), and the National Aeronautics and Space Administration (NASA). (Identified in tables as NSF/NIH/USED/USDA/NEH/NASA.) This report presents the summary of these survey data in online and print formats.

Survey Eligibility
The SED collects information only on research doctorate recipients. Research doctoral degrees are oriented toward preparing students to make original intellectual contributions in a field of study. Research doctorates require the completion of a dissertation or equivalent project and are not primarily intended for the practice of a profession. The SED recognized 18 distinct types of research doctorates in 2011 (table A-1). Professional degrees, such as the MD, DDS, DVM, JD, PsyD, and DMin, are not covered by the survey.

The vast majority of research doctoral degrees are doctors of philosophy (PhD). Of the 49,010 new research doctorates granted in 2011, 97.8% were PhDs; PhDs were 95.8% of research doctorates in 2010 (table A-2). The next most frequently occurring type of research doctorate was the doctor of education, EdD, which accounted for 1.4% of the total in 2011. No other type of doctoral degree accounted for as much as one half of one percent of the new research doctorates in 2011.

Survey Universe
The population eligible for the 2011 survey consisted of all individuals who received a research doctorate from a U.S. academic institution in the 12-month period ending 30 June 2011. The total universe consisted of 49,010 persons in 412 institutions that conferred research doctorates in 2011.

Data Collection
Survey instruments were mailed to institutional coordinators at each doctorate-awarding institution. The institutional coordinators distributed the survey forms to individuals receiving a research doctorate, collected the forms, and returned them to the survey contractor for editing and processing. Data were also collected using Web and telephone versions of the survey. Respondents who did not complete critical survey items were contacted by mail to request response to these items.

A small but growing number of research doctoral degrees are awarded as a part of a joint doctoral program (i.e., a research doctorate recipient studied at more than one institution in pursuit of the doctoral degree). In these instances the survey contractor relies on information provided by the institutions to appropriately attribute the doctorate to the doctorate-granting institution.

The survey collects a complete college education history. Survey staff use the coding manual Mapping the World of Education: The Comparative Database System, augmented with over 3,000 additional institutions from the Europa World of Learning, to code the undergraduate institutions of respondents from foreign countries, about one-third of U.S. doctorate recipients.[1]

Until 1997 the survey was conducted by the National Research Council of the National Academy of Sciences under contract to the National Science Foundation (NSF). NORC at the University of Chicago currently conducts the survey under contract to NSF.

Survey Response Rates
Approximately 93% of the 49,010 individuals who received a research doctorate in 2011 completed the survey instrument (table A-3). This percentage is referred to as the self-report rate in this analysis. Limited records (field of study, doctoral institution, and sex) are constructed for nonrespondents from administrative records of the university—commencement programs, graduation lists, and other public records—and are included in the reported total of 49,010 doctorate recipients for 2011.

Nonresponse was concentrated in certain institutions: 1% of the 412 doctorate-granting institutions accounted for 19% of the total nonrespondents, and 10% of these institutions accounted for 63% of the total nonrespondents.

Counts for previous years were corrected by the addition of data from surveys received after the close of data collection for a given year.

Table A-4 shows item response rates for 2001–11 by variable name. In this analysis, item response rate is the percentage of cases providing data on the item divided by the universe of doctorate recipients eligible to answer that item. On most items, the full universe of doctorate recipients establishes the universe of eligible respondents. However, on a number of items, only a subset of the full universe is eligible to answer the item (see clarifying notes in table A-4). The numbers and percentages in the tables and figures of this report are based on the number of respondents eligible to answer the applicable survey item.

Disclosure Protection
Two strategies for protecting against the statistical disclosure of confidential information provided by SED respondents are used in this report. In the first, used since 2004, data cells having values below a predetermined threshold are deemed to be sensitive to potential disclosure and are suppressed. The symbol "D" replaces the cell value. A suppressed cell may not provide sufficient protection in tables that include marginal totals, as the suppressed data cell values could be computed from the values of other cells in the table. In such cases additional (complementary) suppressions of above-threshold data cells may be necessary.

A second disclosure protection strategy, field aggregation, was also used in this report. This strategy was first applied in Doctorate Recipients from U.S. Universities: Summary Report 2007–08. Field aggregation was applied to data tables 16 and 22 in the current report, which present counts of doctorate recipients classified by fine fields of degree and by either sex (table 16) or race/ethnicity (table 22). Because some fine fields of degree award relatively few doctorates in a single year, the degree counts by race/ethnicity or sex within these fields can be quite small, leading to extensive cell suppression. The field aggregation technique combines data from small fields of degree with the data from related fields, so that the degree counts in the aggregated fields are sufficiently large to protect the confidentiality of respondent information.

A threshold of 25 was determined to be large enough to safely report doctorate recipient counts classified by race/ethnicity or sex. The count of doctorate recipients in each race/ethnicity or sex category of tables 16 and 22 is reported for fields in which at least 25 individuals earn a doctoral degree in a given year, regardless of how small the count may be in a particular category. Counts of doctorate recipients in fields having fewer than 25 doctorates awarded are aggregated with those of one or more related fields until the total number of doctorates in the aggregated field rises to at least 25. The degree count in each race/ethnicity or sex category of these aggregated fields is reported in tables 16 and 22, but the constituent fine fields of the aggregated fields are not displayed.

In 2011, 78 of the 302 fine fields of degree awarded fewer than 25 doctorates. These below-threshold fields were combined with 46 related fields of degree to produce 40 aggregated fields in 2011. Table A-5 lists the aggregated fields that appear in tables 16 and 22 and identifies their constituent fine fields.

Changes to Survey Variables Over Time
Citizenship. The citizenship status variable is used to identify the appropriate citizenship category of respondents, including those who did not respond to the citizenship status survey item on the SED. A new code frame for the citizenship status variable was introduced in 2000.

Code Citizenship category
  0 U.S. native born
  1 U.S. naturalized citizen
  2 Non-U.S. immigrant (permanent resident)
  3 Non-U.S. non-immigrant (temporary U.S. visa)
  4 Non-U.S., visa status unknown
Blank Missing or citizenship unknown

Respondents who indicated a U.S. birthplace but did not report citizenship status were assigned code 0.

Respondents who designated a non-U.S. country for the country of citizenship item but did not respond to the citizenship status item were assigned code 4 for citizenship status. From 1997 to 2003, non-U.S. born respondents who did not indicate their country of citizenship or citizenship status were assigned to code 4 if three out of four geographic variables—place of birth, place of high school, place of college entry, postgraduation location—were non-U.S. locations. Beginning with the 2004 SED the variable "place of baccalaureate institution" replaced "place of college entry" in the assignment of a citizenship code to respondents who did not indicate citizenship status.

For tabulations in this report, code 4 was combined with code 3—that is, counts of doctorate recipients in the temporary visa holder category include non-U.S. citizens with unknown visa status. This is consistent with coding procedures in previous data collections. However, the existence of code 4 allows the data user to exclude cases for which visa status is unknown, if desired. Prospective data users should note, however, that the number of cases in the code 4 group is not sufficient to warrant analysis as a separate citizenship category.

Non-U.S. citizens that did not report a country of citizenship but reported the same non-U.S. country for three out of four geographic variables—place of birth, place of high school, place of baccalaureate institution, postgraduation location—were assigned that reported country as their country of citizenship.

Debt. Since 2001 respondents have been asked to indicate the amount of education-related debt they owe, with separate response categories for graduate and undergraduate education. To estimate overall debt, the midpoint of the chosen range for undergraduate and for graduate debt was selected and summed to yield a total debt amount. Where mean debt levels are presented in this report (i.e., tables 38 and 40), the individual values for debt are assigned as the midpoint of the chosen range for graduate and undergraduate debt. Doctorate recipients who chose the lowest debt category (No debt) were assigned a value of $0 for the computation of mean debt levels. Doctorate recipients who chose the uppermost category ($90,001 and up) were assigned a value of $95,000 for the computation of mean debt levels. All valid responses, including "No debt," were included in the computation of all average debt figures in this report. See item A8 on the survey questionnaire for a complete listing of the debt ranges on which the midpoint figures were based.

Median computation. Since 1994 medians have been computed as follows.
Median age. Months (of birth, baccalaureate, and doctorate) are included in the calculation of median age whenever available. If birth month is missing in the calculation of median age, month value is assigned to the month the doctorate was received.

Time to degree from bachelor's completion. Months are included in the calculation of total time to degree. If months are missing, month values are assigned to the number of days corresponding to the month of June, with a leap-year factor included (i.e., assignment to a value of 151.25).

Time to degree from graduate school entry. Months are included in the calculation of graduate school time to degree. If months are missing in the calculation of graduate school time to degree, month values are assigned to the modal value for doctorate recipients who provided month of graduate entry (i.e., assignment to a value of 243.25, which corresponds to the month of September). Reports published before 2004 reported a different time-to-degree measure, registered time to degree. Comparisons of graduate school time-to-degree data with pre-2004 registered time-to-degree data should be interpreted cautiously. For an explanation of registered time to degree, see the technical notes section of any Doctorate Recipients from United States Universities: Summary Report published before 2004.

Salary. Median salary is calculated from exact salary values when provided by the respondent, and from imputed exact salary values when the respondent selected only a salary bracket. Only salary data from doctorate recipients reporting definite commitments for an employed or a postdoc position are included in median salary calculations.

Postdoctoral plans to stay in the United States. In 1997 the planned postdoctoral location of doctorate recipients began being coded in a new variable using Federal Information Processing Standards (FIPS) codes both for U.S. states and territories and for countries.

Also in 1997, a dichotomous variable was created to index whether the planned postdoctoral location reported by the respondent was in the United States or in a foreign location. This second variable captures a respondent's report of postgraduation location (in the United States or outside the United States) even if the respondent does not indicate a specific state or country.

Race and Hispanic ethnicity. Since 2001 respondents have been asked to first indicate whether or not they are Hispanic/Latino and then to check one or more of the racial group categories (i.e., American Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, black or African American, or white).

Doctorate recipients who report Hispanic ethnicity, regardless of racial designation, are counted as Hispanic. Non-Hispanic respondents who indicate a single race are reported in their respective racial groups. Beginning in 2007, non-Hispanic doctorate recipients who report more than one race are reported in the "Two or more races" race/ethnicity group.

Research doctoral degree. As doctoral degree programs change to meet the needs of students, the orientation of the degrees they award may change from research to professional, and vice versa. Survey staff review degree programs to ensure that the designation of research doctorate remains appropriate. As a result of degree reviews in the past two data collections, survey staff identified several research doctoral degrees that had shifted to a professional orientation. The doctor of music, DM, and the doctor of industrial technology, DIT, were both dropped from the SED in 2008, and graduates who earn these doctoral degrees are no longer included in the SED.

After a multiyear review of doctoral programs offering the EdD degree, most were determined to have a professional orientation and were dropped from the SED in 2010 and 2011, and graduates earning EdD degrees from those programs are no longer included in the SED. As a result, the proportion of EdD degrees among the total number of research doctorate recipients fell from 5.5% in 2009 to 1.4% in 2011. Table A-1 lists the doctoral degrees that were eligible for inclusion in the SED in 2011.

Basic annual salary. Annual salary to be earned in the next year, not including bonuses or additional compensation for summertime teaching or research.

Definite plans to stay in the United States. A respondent is coded as having firm plans to stay in the United States if the reported postgraduation location was in the United States and the reported postgraduation plans were coded "definite."

Definite postgraduation plans. The status of postgraduation plans is coded using the values from item B3 of the survey questionnaire, which indicate whether the doctorate recipient's postgraduation plans were definite at the time the survey was completed.

Field of study. The SED has 302 fine fields of doctoral study, which are grouped into 35 major fields of study. The major field groupings are further aggregated into seven broad fields: life sciences, social sciences, physical sciences, engineering, education, humanities, and other fields. The levels of this variable were derived by grouping related fine fields of study from the field of study taxonomy used in the SED (table A-6). See the survey questionnaire for a full listing of the fine fields of study in 2011.

Doctorate recipients indicate their fields of specialty. Their choices may differ from departmental names. Field groupings may differ from those in reports published by federal sponsors of the Survey of Earned Doctorates (SED). The "general" field categories—e.g., "chemistry, general"—include individuals who either received the doctorate in the general subject area or who did not indicate a particular specialty field. The "other" field categories—e.g., "chemistry, other"—include individuals whose specified doctoral discipline was not among the specialty fields listed.

Median age at doctorate. One-half of the respondents received the doctorate at or before this age. A recipient's age is obtained by subtracting the month/year of birth from the month/year of doctorate. (See "Changes to Survey Variables Over Time," above, for calculation of the median.)

Percentage with master's. This variable is the percentage of doctorate recipients in a field who received a master's degree in any field before earning the doctorate.

Research doctorate. A research doctoral degree is a degree that is oriented toward preparing students to make original intellectual contributions in a field of study. Research doctorates require the completion of a dissertation or equivalent project and are not primarily intended for the practice of a profession.

Time to doctorate. The SED measures the time it takes to complete a doctoral degree in two ways: (1) the time elapsed from completion of the baccalaureate to completion of the doctorate (total time to degree); and (2) the time elapsed from the start of any graduate school to completion of the doctorate (graduate school time to degree). Time-to-doctorate measures herein are reported as medians.

Total time to degree. This variable is the total elapsed time between the baccalaureate and the doctorate, including time not enrolled in school. It can be computed only for individuals whose baccalaureate year is known. Baccalaureate year is often obtained from commencement programs or doctorate institutions when not reported by the recipient. Months are now included in the computation. (See "Changes to Survey Variables Over Time," above, for computation of the median.)

Graduate school time to degree. This variable is the elapsed time from the initiation of graduate study in any program or capacity at any university and the doctorate. This variable can only be computed for individuals who provided the year they started graduate school. Months are now included in the computation. (See "Changes to Survey Variables Over Time," above, for computation of the median.)

U.S. regions of employment. This variable is used to classify the location of U.S. employment after award of the doctorate.

New England Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont
Middle Atlantic New Jersey, New York, Pennsylvania
East North Central Illinois, Indiana, Michigan, Ohio, Wisconsin
West North Central Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota
South Atlantic Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia
East South Central Alabama, Kentucky, Mississippi, Tennessee
West South Central Arkansas, Louisiana, Oklahoma, Texas
Mountain Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming
Pacific and Insular Alaska, California, Hawaii, Oregon, Washington, American Samoa, Guam, Puerto Rico, Trust Territories, Virgin Islands

Appendix Tables

Table Summary Report Data: 2011 Excel PDF
A-1 Types of research doctoral degrees recognized by the Survey of Earned Doctorates: 2011 view Excel. view PDF.
A-2 Research degrees included in the Survey of Earned Doctorates: 2007–11 view Excel. view PDF.
A-3 Survey response rates, 1976–2011 view Excel. view PDF.
A-4 Item response rates: 2001–11 view Excel. view PDF.
A-5 Aggregated fields and their constituent fine fields: 2011 view Excel. view PDF.
A-6 Aggregations used to determine major field of study: 2011 view Excel. view PDF.


[1]  U.S. Department of Education. 1996. Mapping the World of Education: The Comparative Database System (CDS). 3 volumes. Available at Routledge-Taylor & Francis Group. 2006–. Europa World of Learning. Serial and online database, London.