PhD completion rate is one of the most important measures used in the National Research Council rankings1 and also one that we can influence by our policies and practices. As deans, chairs, and directors of graduate studies set goals, determining appropriate completion targets should be a priority. With the NRC survey results about to be released, now is the time to review our own data and strategize how we might improve. This report presents our data within the context of national studies.
Ph.D. completion rates are usually reported for a 10-year period. The Council of Graduate Schools (CGS) reports an overall 57% 10-year completion rate2. UA’s National Research Council programs also have a 57% completion rate for 10 years,3 but the data are not completely comparable because our data are only for students who were fulltime throughout their graduate career while the CGS data includes part-time students and students who stopped out. Logically one would expect higher completion rates for students who were full time throughout their career.
Not surprisingly, completion rates vary by discipline. Like previous studies, CGS finds differences in completion rate between men and women, between majority and minority students, and between domestic and international students. Ph.D. students in Engineering are most likely to complete within 10 years (64%), closely followed by Life Sciences (62%). Physical Science and Math and Social Sciences complete at a rate of 55%, and Humanities students trail at 47%. Majority students complete about 2% more than underrepresented minority students; men complete at about 4 points higher than women; international and domestic students complete at about the same rate after 10 years, but international students have a shorter time to degree. Patterns at UA follow national trends, as shown in the graph below.
Because the numbers of women in some disciplines are small (and because the climate for women may have changed since the mid 1990s), the next analysis considers also the 98/99, 99/00, 00/01 cohorts (a total of 1494 UA students). The graph below shows completion rates by gender within disciplines.
Men were 60% of entering cohorts and 63% of graduates. Women were 40% of entering cohorts and 37% of graduates. The difference in completion rate is not statistically significant. Only the gender difference in Science, Engineering, and Math is statistically significant (53% of men had completed by Summer 2006 compared with 41% of women).
The NRC measure is based on 6 year (8 year for humanities) completion rates for cohorts entering PhD programs between Fall 1996 and Fall 2000 (Fall 1996 to Fall 1998 for Humanities). NRC selected the shorter time frame to encourage U.S. universities to set a goal of shortening time to degree. National studies point to problems associated with low completion rates and long time to degree, such as:
decreasing interest in STEM fields by domestic students partly because of the long time to degree coupled with long postdoctoral study, and
mounting debt among graduates, exacerbated by very long times to degree.
Because NRC considers only those students who are fulltime throughout their graduate career, the numbers for some programs are small4. Time to degree is counted from the admission to the Ph.D. program. Among all NRC programs at UA, the completion rate for 6 years (8 for humanities) was 44%, with males completing at a rate of 48% and women at 38%. National results are not yet available, but preliminary data sharing by AAU schools suggests that our results are lower than many of our peers. While one could argue that low completion rates do not necessarily reflect low quality, they do indicate a serious inefficiency and a poor use of our limited resources.
Time to Degree
Time to degree in the NRC study is measured by looking at students completing in 2003/2004 through 2005/2006 and counting backwards from their first admission to Ph.D. programs. UA’s median time to degree for all NRC programs was 5 years, with females averaging 5.5 years. Completion rates and time to degree are uncorrelated, meaning that students in programs with higher completion rates are not necessarily any faster to graduate. Duke reports the same result. Logically, however, improving time to degree will increase completion rates since many of our students finish within 7 or 8 years and are hence not counted in the six year rates.
UA Quantitative Results
The table below presents our data by NRC program for the six year (eight for arts and humanities) period. Given the small numbers, these data will have considerable random variation and should be interpreted with caution. Direct comparison between programs may be misleading since some programs require a master’s degree for admission while others admit directly to the Ph.D. These data were shared with departments prior to submission to NRC, and departments had an opportunity to verify them.
Table 1. PhD completion and Median Time to Degree by Program