One week after the American Enterprise Institute (AEI), a conservative Washington-based think tank, released a report scrutinizing colleges and universities with low six-year graduation rates, the American Association of State Colleges and Universities (AASCU) issued a policy brief criticizing the way graduation rate information is collected.

“A criticism of our current graduation rate metric is that it is based on an outmoded model of student behavior that assumes linear and timely progression through a single institution. This model fails to recognize the ‘swirling’ behavior that involves alternating full- and part-time attendance, enrollment in multiple institutions, transfer and stopping out,” according to the AASCU’s brief.

The U.S. Education Department’s National Center for Education Statistics (NCES), the source of graduation rate data widely used in U.S. higher education research, developed the Graduation Rate Survey as part of its Integrated Postsecondary Education Data System as a means of tracking students over a period of several years. The survey, however, does not include part-time students, adults with prior college coursework, and students who take longer than the allotted six-years to graduate.

“By not taking into account students’ actual enrollment behavior and by failing to encompass much of what institutions do, current graduation rate data lead to misleading conclusions about institutional performance,” the policy brief says.

Last week, the AEI reported that noncompetitive institutions — those that have less selective admissions criteria — graduate, on average, 35 percent of their students, while competitive institutions graduate 88 percent. Less competitive and competitive schools do better than noncompetitive institutions, but the national average graduation rate is less than 60 percent. Researchers say the high graduation rates among competitive schools are to be expected because they’re admitting highly talented students.