Dual enrollment: Getting students to a degree more efficiently?

I was recently asked whether there's any research indicating that dual enrollment program participants ultimately earn fewer total credits when completing a postsecondary degree. A 2009 Florida study does provide at least a partial response to this question.

The report notes that 40% of students surveyed at Florida's largest universities believed that "acceleration credits" (dual enrollment, as well as IB, AP and other options) allowed them to "progress through college in a shorter time period". Data support these students' perceptions. Students graduating from Florida's state universities in the 2006-07 academic year who had completed acceleration credits attempted an average of 128 credit hours of college courses, whereas their average peer who had not earned acceleration credits attempted 140 credit hours.

Unfortunately, the study doesn't separate the results by the type of accelerated credit students earned. Nor do the authors speculate why students earning acceleration credits of any kind finished a college degree with fewer credits. And granted, this is just one study in just one state. However, it's hard not to be at least a little interested reading that "This difference equates to almost a semester of college courses, which represents a substantial savings in higher education costs to both the state and students. The state benefits from the freed instructional slots and classroom space that allow other students to progress through these classes."

One might argue that students earning acceleration credits are more academically motivated--but on the other hand, there are various ways academically motivated students might earn more college credits than the average student. Academically motivated students might choose double majors (or even triple-majors--this author was one of those crazy people)--although students in the Florida report noted that acceleration credit allowed them to pursue double majors and dual degrees. Students in general--including academically motivated students--might also earn more total college credits by switching majors mid-college careers (been there, done that, too), turning all those credits that once went towards a major into a mighty expensive minor, with a lot of excess credit hours in tow. More academically motivated students might even have greater motivation to switch colleges (transitioning to a more selective college, for example), resulting in credits that are only recognized as "electives" at College #2.

Another thought might be that dual enrollment courses allow students to "try on" different academic disciplines at a more rigorous level before starting college, so that students are less likely to accumulate too many credits in one discipline before switching degree areas, if they decide to change majors at all. And--particularly when students complete dual enrollment courses on a college campus---dual enrollment allows students to "try on" a college at the same time they "try on" a discipline, so that students may decide to apply at (or decide to avoid!) the postsecondary institution where they had their dual enrollment experience, again avoiding those credit hours not recognized at College #2 after things at College #1 don't work out.

I would love to see more research on this point--are dual enrollment students less likely to change majors once they enter college? Are they more likely to enroll in the postsecondary institution partnering in the dual enrollment experience than their peers in the same geographic area who did not participate in dual enrollment? Are there other factors that lead dual enrollment students to complete a college degree in fewer credit hours? Or in fact, will studies in other states not bear the same results as those in Florida? In an era where states are trying to simultaneously raise college completion and attainment rates and keep postsecondary costs down, such research would be extremely valuable.