TIME-TO-DEGREE (TTD)THROUGHOUT THIS BOOK, we measure TTD as elapsed time-to-degree,
which is the number of years that have elapsed between entering a PhD
program and the time the PhD is awarded.Drawbacks. TTD can be calculated only for those students who earn the
PhD. Furthermore, the mean TTD for a group of students is greatly affected by the years since the group began graduate study. The mean TTD
for students who began 8 years ago must, by definition, be 8 years or
fewer, whereas the mean TTD for those who began 10 years ago can include some degree times that are longer than 8 years. Thus when comparisons are made between two time periods, the means must be truncated to include only those students whose potential years in the program
are the same.Calculation. TTDmean = [Σ(PhD date – Entry date)/365]/C, where C is
the absolute number of students earning the PhD.Alternative versions.
|• ||Total time-to-degree: Elapsed time from bachelor's degree to completion of the PhD degree. This measure is used when dates of PhD
entry are not available.|
|• ||Registered time-to-degree: Omits terms when student has not been
|• ||Half-life: The time in years necessary for half of an entering cohort
to earn the PhD. This measure was created by C. Anthony Broh,
while he served as registrar at Princeton University, to facilitate comparisons that capture both the pace and the extent of completion. It
can be compared for groups entering in different years.|
CUMULATIVE COMPLETION RATE (CCR)
The completion rate is the percent of an entering cohort who have
earned the PhD degree. Greatly affected by time elapsed since entry, it
should be standardized by the number of years since entry. The CCR is
Questia, a part of Gale, Cengage Learning. www.questia.com
Book title: Educating Scholars: Doctoral Education in the Humanities.
Contributors: Ronald G. Ehrenberg - Author, Harriet Zuckerman - Author, Jeffrey A. Groen - Author, Sharon M. Brucker - Author.
Publisher: Princeton University Press.
Place of publication: Princeton, NJ.
Publication year: 2010.
Page number: 300.
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