The most logical reason to focus on "time to degree" for doctoral students is that most of them say they want to finish -- and most graduate departments say the same thing. People are happier and programs are more efficient.

But a new national study suggests another key reason -- at least in social science disciplines: Those who finish earlier than others do are more likely to land jobs on the tenure track. Of those in the national sample whose first job was on the tenure track, the median time to completion of Ph.D. was 6.5 years. For those whose first job was an academic position off the tenure track, the median time to completion was 7.5 years.

The data are from "Does Time-to-Degree Matter?," a new analysis of the "Social Science Ph.D.'s -- Five + Years Out" project, which has been yielding a series of insights into the path students take in graduate school and beyond. The work is done at the University of Washington's Center for Innovation and Research in Graduate Education and is based on national data on doctorates in anthropology, communications, geography, history, political science and sociology.

Maresi Nerad, director of the center and associate graduate dean at the university as well as principal investigator on the research, said that the finding has several possible implications. One is that those doing the hiring view "time to degree" (fairly or not) as an indicator of quality. She said that the findings can suggest inappropriate considerations (favoring younger candidates) or skepticism about whether someone taking a long time to finish a dissertation may also take a long time to finish a first book or other research projects.

While Nerad's research has stressed the importance of helping graduate students finish in a timely manner, she said that hiring departments' preferences could play out in good or bad ways if they influence doctoral students' behavior. To the extent that students are motivated to get through on time (and that departments help them do so), it's all for the good, she said. But if this encourages students to pick only "safe" topics -- those assured of a reasonably timely completion -- for dissertations, that's not so good.

Other findings from the new analysis support the idea that graduate programs need to spend more time on helping graduate students prepare for their careers -- not just their dissertation defenses. In surveys of Ph.D.'s wherein they evaluate their programs, those who finished doctorates sooner than others were more likely to give "excellent" rankings to both their mentoring and training and also to "professionalization" activities, which include programs to prepare graduate students for careers (both finding jobs and being socialized into academic life).

Those findings are important, Nerad said, because they show that professionalization need not lengthen the duration of a graduate program. Some professors who believe a doctoral program should focus strictly on academics have suggested that adding programs to help with jobs could delay dissertation completion -- and Nerad said the data suggest otherwise.

In addition, Ph.D. recipients gave higher marks for overall satisfaction to programs with professionalization activities than to those without.

Nerad stressed that the reasons any individual doctoral student completes a program in a set time period relate to a variety of factors -- both personal, those that relate to the student's project, and those that relate to the program. But it's also clear, she said, that for many people "time to degree can be an indicator of program quality."

Looking ahead, Nerad said that some fields may see changes in the duration of programs because of the economic downturn. In fields in which job prospects in academic appear bleak, especially in the humanities, graduate students may "opt to stay a little longer."

But in fields in which there are good non-academic jobs, or where postdocs have become the norm prior to permanent employment, the shifts may be minimal, she said.