Comparing graduation in 6 years is a way to penalize colleges that serve students with lower average SES & SATs

A. Two colleges; one has retention rate 90% of the other. After 4 years, the graduation rate of the lower-retention college will be 66% of the other. 66% looks much worse than 90%.

B. Retention rate is easy to calculate, so use this to compare colleges and for any particular college to set a target.

Net withdrawal = Gross withdrawal – Returns
Net withdrawal rate = (#students at year n – # newly matriculated students + #students graduate -#students at year n-1)/#students at year n-1
Retention rate = 1- net withdrawal rate
= (#students at year n + #students graduate – # newly matriculated)/#students at year n-1

C. Even better, compare retention rates after controlling for average SES (socioeconomic status) and SAT/ACT scores.

Predicted retention rate (AVSES, AVSAT) = a + b*AVSES + c*AVSAT + d*AVSES*AVSAT (based on a regression analysis over all 4+ year colleges)

(See this article to understand why this is relevant.)

Compare actual retention rate/ predicted retention rate or actual retention rate – predicted retention rate

On that basis, decide whether efforts are needed to boost retention or whether efforts to boost retnetion are working.

D. Refine B & C to take into account student loads

Replace student numbers with numbers of effective full time students.
(If students in a college tend to study part-time but not withdraw, then that college is not a worse college for the fact that students take longer to graduate.)

E. Inquire into the ideological background of officials who promote the use of 6-year graduation rates.

Is the move to tie funding to 6-year graduation rates a backdoor way to punish public education for wanting to serve all students, not only those who are already advantaged (via higher SES and SAT) on entry?

About Peter J. Taylor
Peter Taylor is a Professor at the University of Massachusetts Boston where he teaches and directs undergraduate and graduate programs on critical thinking, reflective practice, and science-in-society. His research and writing focuses on the complexity of environmental and health sciences in their social context, incl. Unruly Complexity: Ecology, Interpretation, Engagement (U. Chicago Press, 2005) and Nature-nurture? No (2014, On reflective practice, see Taking Yourself Seriously: Processes of Research & Engagement (with J. Szteiter, 2012,

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