Technical Notes

Purpose. The SED collects data on the number and characteristics of individuals receiving research doctoral degrees from U.S. academic institutions.

Data collection authority. The information collected by the SED is solicited under the authority of the National Science Foundation Act of 1950, as amended, and the America COMPETES Reauthorization Act of 2010. The Office of Management and Budget control number is 3145-0019, expiration date 30 April 2022.

Survey contractor. RTI International.

Survey sponsors. The SED is sponsored by NCSES within NSF and by NIH, ED, and NEH.

Frequency. Annual.

Initial survey year. Academic year 1957–58.

Reference period. Academic year 2020–21 (1 July 2020 to 30 June 2021).

Response unit. Individuals.

Sample or census. Census.

Population size. 52,250.

Sample size. Not applicable.

Target population. The population for the 2021 SED consists of all individuals receiving a research doctorate from a U.S. academic institution in the 12-month period beginning 1 July 2020 and ending 30 June 2021. A research doctorate is a doctoral degree that (1) requires completion of an original intellectual contribution in the form of a dissertation or an equivalent culminating project (e.g., musical composition) and (2) is not primarily intended as a degree for the practice of a profession.

The SED recognized 18 distinct types of research doctorates in 2021 (table A-1). Recipients of professional doctoral degrees, such as MD, DDS, DVM, JD, DPharm, DMin, and PsyD, are not included in the SED.

The doctor of philosophy (PhD) constitutes the vast majority of research doctoral degrees. Of the 52,250 new research doctorates granted in 2021, 98.4% were PhDs (table A-1). The next most frequently occurring type of research doctorate was the doctor of education (EdD), which accounted for 0.9% of the total in 2021. No other type of doctoral degree accounted for more than 0.3% of the new research doctorates in 2021.

Sampling frame. The sampling frame of doctorate recipients is created by first identifying all institutions that confer research doctorates and then identifying all individuals receiving a research doctorate from those institutions in the 12-month period ending 30 June 2021. The list of institutions is based principally on the institutions in the prior survey cycles augmented by any new institutions on the Integrated Postsecondary Education Data System (IPEDS) and other higher education resource databases. The list of doctorate recipients is created from administrative sources such as commencement lists from the institutions and commercial databases of doctorate dissertations. For 2021, 456 research doctorate granting institutions were identified; however, 8 of these institutions reported zero graduates, and 12 institutions refused to provide lists of graduates. For 11 of the 12 refusing institutions, the survey contractor was able to construct graduate lists using secondary data sources. Thus, the total universe consisted of 52,250 persons in 448 institutions that conferred research doctorates in 2021.

Sample design. The SED is a census.

Data collection. SED collects data using two modes: self-administered Web survey and computer-assisted telephone interviewing (CATI).

The self-administered Web survey is the primary mode of SED completion. When students apply for graduation, institutional coordinators at the universities give students the link to the survey registration website. Students who sign up at the survey registration website receive PIN and password information via e-mail, as well as the URL of the SED Web survey. The proportion of SED completions using the Web has increased each year since it was introduced in 2001, and it reached 97.6% in 2021.

Nonrespondents are contacted by e-mail and mail to complete the Web survey. If the series of follow-up e-mails and mailings is unsuccessful, the survey contractor attempts to reach nonrespondents to complete an abbreviated survey by CATI. Approximately 2.4% of SED completions were from CATI in 2021. At the end of data collection phase, institutional coordinators are contacted to obtain information on a small number of critical SED data items for nonrespondents from their institution.

A small but growing number of research doctoral degrees are awarded as a part of joint doctoral programs (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 one of the doctorate-granting institutions.

The survey collects a complete college education history. To code U.S. postsecondary degree-granting institutions, survey staff use the IPEDS institution codes. To code the degree-granting institutions of respondents from foreign countries, survey staff maintain a database of foreign institutions, updating it annually to include new entries for foreign institutions reported by SED respondents. About one-third of 2021 U.S. research doctorate recipients received undergraduate degrees from foreign institutions.

Mode. In 2021, 97.6% of survey responses were obtained via the Web survey and 2.4% via CATI.

Response rate. Of the 52,250 individuals who received a research doctorate in 2021, 91.5% completed the survey (table A-2). Additional information on response rate can be found below, under “Nonresponse error.”

Data editing. Approved automated edits are applied to the SED, a number of which pertain to the education history section.

Imputation. No imputation was used in producing the 2021 SED Doctorate Records File (DRF) except for the following variables:

• Age at doctorate. Months (of birth and doctorate award) were included in the calculation of median age whenever available. If birth month was missing, the month value was randomly imputed.
• Time to degree from bachelor’s completion. Months (of bachelor’s completion and doctorate award) were included in the calculation of total time to degree. If months were missing, month values were logically imputed to the modal value for doctorate recipients who provided month of bachelor's completion and converted to the number of days corresponding to that month.
• Time to degree from graduate school entry. Months (of graduate school entry and doctorate award) were included in the calculation of graduate school time to degree. If months were missing, month values were logically imputed to the modal value for doctorate recipients who provided month of graduate entry.
• Time to degree from doctoral program entry. Doctoral program entry is based on master’s degree program entry if the master’s degree was at the doctoral institution in the same fine field of study or if it was a prerequisite to the doctorate; otherwise, it is based on doctoral program entry. Months are included in the calculation of doctoral program time to degree. If the month of entry used in the calculation (master’s degree program entry or doctoral program entry) was not reported, the entry month was logically imputed to the modal value for all cases that did report the entry month in the academic year the case was added to the doctoral records file (typically the academic year matching the graduation date of the case).

For variables with item nonresponse that are not imputed, responses with missing data are omitted from the estimates published in the data tables and figures. Although most variables in the published data have relatively low nonresponse rates, their nonresponse rates vary (see "Nonresponse error," below); use caution when interpreting estimates derived from unimputed variables.

Weighting. Survey data were not weighted.

Variance estimation. The SED is a census of all research doctorates with no sampling, so survey totals have no sampling variability.

Disclosure protection. To protect against the disclosure of confidential information provided by SED respondents, data cell values based on counts of respondents that fall below a predetermined threshold are suppressed in the data tables. Secondary or complementary suppressions are applied as needed to prevent reconstruction of the data cell values from primary suppressions. Beginning in 2021, the detailed fields in the data tables are based on the aggregation of SED-CIP fields such that each detailed field contain 47 or more in the data cell. All suppressed values in the data tables are replaced with “D.”

Sampling error. Not applicable because the SED is a census.

Coverage error. Due to the availability of comprehensive lists of doctorate-granting institutions and the institutions’ high levels of participation in the survey, coverage error of institutions is minimal. Because the graduate schools collect the survey data from degree recipients at the time of doctorate completion, coverage error for the universe of doctorate recipients is also minimal. Comparisons of the institutions and the number of research doctorate recipients covered by the SED with the total number of doctorate recipients (including non-research doctoral degree recipients) reported by institutions to the National Center for Education Statistics confirm that there is minimal coverage error of doctorate recipients. Institutions that begin to confer research doctorates are invited to join the SED. If a university that confers research doctorates does not wish to participate in the SED, slight undercounts may result. In 2021, 12 doctorate-granting universities declined to fully enumerate their doctorate recipients for academic year 2021. Information on the graduates for all of these institutions were found from other sources, such as ProQuest.

Nonresponse error.

• Unit nonresponse. Of the 52,250 individuals who received a research doctorate in 2021, 91.5% completed the survey (table A-2). This percentage is referred to as the self-report rate. Skeletal records for nonrespondents appear on the data file and contain a limited number of SED critical data items (doctoral institution, year of doctorate, field of doctorate, type of doctorate, and, if available, baccalaureate institution, master’s degree institution, and sex) that are constructed for nonrespondents from administrative records of the university, such as commencement programs, graduation lists, and other public records. These nonresponding cases are included in the reported total of 52,250 doctorate recipients for 2021.

Nonresponse was concentrated in a small number of institutions: 7 of the 448 doctorate-granting institutions accounted for nearly 25% of the total nonrespondents, and 22 institutions accounted for 50% 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.

• Item nonresponse. Among the 52,250 individuals who received a research doctorate in 2021, item nonresponse rates for the five key SED demographic variables—sex, citizenship, country of citizenship, race and ethnicity, and location after graduation—range from 0.0% for sex to 7.9% for location after graduation. Table A-3 shows item response rates for 2011–21 for all variables, by variable name (see clarifying notes in the table).

Measurement error. The most likely source of measurement error in the SED is attributable to incomplete or vague information for degree or dissertation field of study provided by respondents or degree-granting institutions, and for educational history provided by respondents. For field of degree, some respondents (or institutions) fail to provide a degree code and instead provide a text string that must be manually coded by the survey contractor. Similarly, some aspects of the educational history timeline—including the field of study for earned associate’s, bachelor’s, or master’s degrees—require manual coding. When manual coding is required, a pair of trained reviewers independently code each text entry, and any discrepancies between the two coders are resolved by a third, more expert reviewer. All manual coding is subject to a final review by NCSES. Generally, the percentage of responses in these data requiring manual coding is low. In 2021, 1.6% of doctorate fields of study were manually coded, as well as 1.8% of associate’s degree fields, 0.7% of bachelor’s degree fields, and 1.3% of master’s degree fields.

Changes in survey coverage and population. For the 2021 cycle, one institution was added to and one institution was removed from the SED universe.

Changes in questionnaire. The following changes were made to the questionnaire in 2021:

New questions.

• Coronavirus Disease 2019 (COVID-19) module. A special COVID-19 module was added in 2021 to capture the COVID-19 pandemic’s impact on the respondents’ graduate experiences and career plans.

The respondents were first asked whether they experienced one of six impact areas as a result of the pandemic: delay in their doctoral degree completion timeline; disruption in their research; reduction or suspension of their doctoral studies; change in their immediate postgraduate employment or education plans; change in longer-term career plans or goals; or change in their plans about where to live in the year after graduation. Respondents were also asked to report any other changes to their graduate experience or career plans.

For each affirmative response, an open-ended follow-up question asked the respondents to elaborate on how they were affected. The open-ended verbatims were coded and this data is available to the restricted-use file licensees as a special analysis file.

Questions dropped.

• Joint degree questions. Questions that asked whether any of the respondent’s postsecondary degrees was part of a joint degree program.
• Same position with the same employer. Questions that asked the respondents who worked during their doctoral studies whether they plan to seek a new employment after receiving their doctoral degree.

Questions changed.

• Educational history. Prior to 2021, respondents’ educational history was asked chronologically, starting with an associate’s degree, bachelor’s degree, master’s degree, and then professional doctoral degree.

In 2021, the education history section was changed to a table format in which respondents can select all the postsecondary degrees received, up to nine degrees. Based on the degrees reported, follow-up questions asked about each type of degree, including any professional doctorate being earned.

• Faculty position. Beginning in 2021, faculty position is asked only when respondents reported their employer is a college or university. Previously, faculty position was asked of all respondents who reported their employer as an education institution, including pre-collegiate institutions.

Question response options changed.

• Type of employer. The first response option was changed to “for-profit company or organization” from “industry (for profit).” The second option was changed to “nonprofit organization (including tax-exempt, charitable organization and private foundation)” from “nonprofit organization (including private foundation).”

Changes in reporting procedures or classification.

• Citizenship. The citizenship status variable is used to identify the appropriate citizenship category of respondents, including the citizenship category of respondents who did not respond to the citizenship status survey item. The code framework for the citizenship status variable is outlined below.

Respondents who indicated a U.S. birthplace, regardless of what they reported for citizenship status, were assigned code 0.

In 1999, code 4 (non-U.S., visa status unknown) was introduced and data were back-coded through 1997. 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, and 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 for 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 microdata user to exclude cases for which visa status is unknown. 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 who 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, and 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 median debt levels are presented in this report (i.e., table 4-4 and table 4-5), 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 median debt levels. Doctorate recipients who chose the uppermost category available prior to 2020 ($90,001 or more) were assigned a value of $95,000 for the computation of median debt levels. In 2020, additional response options were added at the upper range for graduate debt with the highest being $160,001 or more. Doctorate recipients who choose this uppermost category are assigned a value of $165,000 for the computation of median debt levels. All valid responses, including “no debt,” are included in the computation of all median debt data in the data tables.
• Field of study. Beginning in 2021, field of study and doctorate dissertation field data are collected using a modified version of the 2020 Classification of Instructional Programs (CIP) codes maintained by the National Center of Education Statistics (NCES). All data are now reported using the new SED-CIP taxonomy (table A-4). The SED-CIP modifications are as follows:
• Over 50 degree fields collected in SED prior to 2021 but not in the 2020 CIP were added. These SED-CIP codes are noted in table A-5 and table A-6 with a letter suffix other than “a” to the associated CIP code that ends with “a.”
• The exclusion of CIP fields that are not eligible for the SED, which are CIP 12 (Culinary, entertainment, and personal services), CIP 28 (Military science, leadership, and operational art), 32 (Basic skills and development/remedial education), 33 (Citizenship activities), 34 (Health-related knowledge and skills), 35 (Interpersonal and social skills), 36 (Leisure and recreational activities), 37 (Personal awareness and self-improvements), and 53 (High school/secondary diplomas and certificates) series codes.
• The limitation of the CIP 46 (Construction trade), 47 (Mechanic and repair technology/technicians), and 48 (Precision production) series codes to associate’s degree fields only.
• The conversion of the CIP 60 (Health professions residency/fellowship) and 61 (Medical residency/fellowship) series codes to SED-CIP 70 and 71 series codes, respectively, to capture the research fields for doctorate dissertation fields only.

With the new SED-CIP codes introduced in 2021, the survey now collects over 1,600 fields for the field of study reporting, compared to the 334 field codes collected in the previous years. The SED-CIP codes are aggregated into 300 detailed fields, 66 major fields, and 16 broad fields, which are used for reporting in the data tables (table A-4). This new SED-CIP taxonomy includes multidisciplinary/interdisciplinary sciences and multidisciplinary/interdisciplinary studies to capture and track emerging fields. The complete SED-CIP fields with corresponding detailed, major, and broad fields are in table A-5. For more details on the effect of the new taxonomy, see the NCSES Working Paper Survey of Earned Doctorates Field of Study Taxonomy Changes in 2021 and Impact on Trend Data.


To facilitate the trend data comparison with prior years, a crosswalk was created of the SED-CIP codes to the SED historical field of study, which were aggregated into the SED historical broad and major fields (see table A-6). This results in generally comparable historical broad and major fields with some limitations. Specifically, each SED-CIP code mapped to an SED historical field of study code might not be the code the respondent would have chosen from the previously used SED historical field of study list. For example, it is not known how respondents who reported the new SED-CIP field of “electrical engineering and computer science” in 2021 would have chosen their field under the SED historical field of study list that includes two separate fields “electrical engineering” and “computer science.”

Beginning in 2015, the broad field of study of “physical sciences” was broken out into two separate broad fields: “physical sciences and earth sciences” and “mathematics and computer sciences.” Also beginning in 2015, the major fields of “mathematics and statistics” and “computer and information sciences” are listed under the new broad field of “mathematics and computer science.” Prior to 2015, these major fields were listed under physical sciences.

• Functional limitations (previously, disability). Beginning in 2012, the functional limitations items assess both the presence and severity of functional limitations in each of several domains, which do not precisely overlap with the domains in prior surveys.
• Median computation. Since 1994, medians have been computed as outlined below. When months are included, they are converted to the number of days corresponding to the first day of the month. In 2017, the method for accounting for leap days changed to reflect the actual number leap days during the time period specified, rather than the prior method of adding 0.25 days to each year.
• Median age. Months (of birth and doctorate award) are included in the calculation of median age whenever available. Beginning in 2015, if birth month is missing, the month value is randomly imputed. Prior to 2015, the missing month value was 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 modal value for doctorate recipients who provide month of bachelor's completion and converted to the number of days corresponding to that month.
• 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. 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 of any Doctorate Recipients from United States Universities: Summary Report published before 2004.
• Time to degree from doctoral program entry. This variable was first included in 2015. Doctoral program entry is based on master’s degree program entry if the master’s degree was at the doctoral institution in the same fine field of study or if it was a prerequisite to the doctorate; otherwise, it is based on doctoral program entry. Months are included in the calculation of doctoral program time to degree. If the month of entry used in the calculation (master’s degree program entry or doctoral program entry) was not reported, the entry month is assigned to the modal value for all cases that did report the entry month in the academic year the case was added to the doctoral records file (typically the academic year matching the graduation date of the case).
• Race and Hispanic ethnicity. Since 2001, respondents have been asked to first indicate whether they are Hispanic or Latino and then to check one or more racial group categories (i.e., American Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, Black or African American, or White).

In data tables, doctorate recipients who report Hispanic or Latino ethnicity, regardless of race, are counted as Hispanic or Latino, and as of 2013, those who did not answer the Hispanic or Latino question are counted as “ethnicity not reported.” Respondents who indicate that they are not Hispanic or Latino and indicate a single race are reported in their respective racial groups, except for those indicating Native Hawaiian or Other Pacific Islander, who are included in “other race or race not reported.” Beginning in 2007, doctorate recipients who indicate they are not Hispanic or Latino and indicate more than one race are reported in the group “two or more races.”

• 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 past data collections, survey staff identified several research doctoral degrees that 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 the graduates (approximately 40 to 60 per year) 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 0.9% in 2021. Table A-1 lists the doctoral degrees that were eligible for inclusion in the SED in 2021.

• Salary. Median salary is calculated from exact salary values when provided by the respondent. Salary imputation was dropped as of 2015 due to the increase in exact salary response rate. From 2011–14, if a respondent selected a salary range instead of providing an exact salary value, exact salary values were imputed for median salary calculation purposes by applying hot-deck imputation based on salary range and other relevant respondent characteristics. Prior to 2011, median salary was calculated directly from the salary range values via interpolation methods, and exact salary values were not used in the calculation of median salary. Only salary data from doctorate recipients reporting definite commitments for employment or for a postdoc position in the United States are included in median salary calculations.

• Basic annual salary. Annual salary expected to be earned from the doctorate recipient's principal job in the next year after receiving the doctorate, not including bonuses or additional compensation for summertime teaching or research.
• Carnegie classification (institution categories). In this report, four types of doctorate-granting institutions identified in the figures and tabulations are defined according to the Carnegie classification scheme as updated in 2018: doctoral very high research, doctoral high research, doctoral/professional universities, and other universities (comprised of all other classifications). Institutions are classified according to their aggregate and per-capita levels of research activity, using indicators of research and development expenditures, staffing (including postdoctoral appointees and other nonfaculty research staff with doctorates), and doctoral conferrals in science and engineering and other fields.
• Definite plans to stay in the United States. A respondent is coded as having definite plans to stay in the United States if the reported postgraduation location was in the United States and the reported postgraduation plans for employment or postdoc were coded “definite.”
• Definite postgraduation plans. The status of postgraduation plans is coded using the values from item B2 of the survey questionnaire, which indicate whether the doctorate recipient’s postgraduation plans for employment or a postdoc position were definite at the time the survey was completed.
• Field of study. The SED collects data on over 1,600 fields of study which are grouped into 300 detailed fields, 66 major fields and 16 broad fields. See table A-5 for a full listing of the SED-CIP codes and their alignment to the detailed, major, and broad fields of study in 2021. See table A-6 for the SED-CIP to SED historical field of study crosswalk.

Doctorate recipients report their fields of study and doctorate dissertation. Their choices may differ from departmental names. Field groupings may differ from those in other reports published by federal sponsors of the 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 “nec” or not elsewhere classified field categories (e.g., “chemistry nec”) include individuals whose specified doctoral discipline either did not fit into aggregation within major fields or who reported the “other” CIP code (i.e., “chemistry, other”).

• 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 and year of birth from the month and year of doctorate.
• 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 oriented toward preparing students to make original intellectual contributions in a field of study and is not primarily intended for the practice of a profession. Research doctorates require the completion of a dissertation or equivalent project.
• Time to doctorate. The time it takes to complete a doctoral degree is measured in three ways: (1) the time elapsed from completion of the baccalaureate to completion of the doctorate (total time to degree), (2) the time elapsed from the start of any graduate school program to completion of the doctorate (graduate school time to degree), and (3) the time elapsed from the start of the doctoral program. Time-to-doctorate measures herein are reported as medians. In 2017, the method for accounting for leap days changed to reflect the actual number leap days during the time period specified, rather than the prior method of adding 0.25 days to each year.
• 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.
• 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 award of the doctorate. This variable can be computed only for individuals who provided the year they started graduate school. If an individual did not respond to this question, which asks for the month and year of first entry into any graduate school, then values for graduate school month and year of entry are imputed from the month and year of entry into the most recent master’s degree program or, if that is missing, the month and year of entry into the doctoral degree program. Months are included in the computation.
• Doctoral program time to degree. This variable is either (1) the elapsed time from the master’s degree program entry, if the master’s degree was awarded at the doctoral institution and was in the same fine field as the doctorate or if the master’s degree was a prerequisite to the doctoral program until doctorate completion; otherwise, it is (2) the elapsed time from the doctoral program entry until doctorate completion. This variable is only computed for academic year 2015 and later doctorates.
• U.S. regions of employment. This variable is used to classify the location of U.S. employment after award of the doctorate.