II-29a: Median Years to Doctorate,* by Primary Type of Financial Support and Broad Field of Study** for PhDs Graduating 2011–2013
* Time in doctoral program is measured as the difference between the month and year the doctorate was granted and the month and year the student started his or her doctoral program (or most recent master’s degree program, if the master’s was earned at the same institution as the doctorate).
** Life sciences includes agricultural sciences and natural resources; biological and biomedical sciences; and health sciences. Physical sciences includes mathematics and computer and information sciences. Social sciences includes psychology.
Source: National Science Foundation, National Center for Science and Engineering Statistics, Survey of Earned Doctorates (SED; a custom tabulation of SED data was prepared for the Humanities Indicators by NORC at the University of Chicago).
The Survey of Earned Doctorates (SED) offers researchers several ways of measuring “time-to-degree.” The survey yields data on both time since completing undergraduate studies and time since first taking a graduate course. The Humanities Indicators uses as the basis of its calculation of time to degree a third type of data supplied by the SED: the date the student began studies in the program that conferred his or her doctoral degree—or master’s degree, if earned at the same institution as the doctorate (see question A8 on the 2012–2013 questionnaire). The difference between this date and the date of doctorate completion yields a measure of time to degree that is not inflated by what for some students (especially those who earn their master’s and doctoral degrees at different institutions) are lengthy pauses between degrees.