Two weeks ago I wrote about the overwhelming research evidence that community college students aren't doing as well in online classes as they are in face-to-face traditional classes. Students are failing in higher numbers and getting lower grades. That remains true, but it isn't the whole story.

Peter Shea, who is the associate provost of online learning at the University of Albany—SUNY, contacted me to share his research findings. Community college students who take online courses are more likely – 25 percent more likely to be exact – to complete their two-year associate degree or some sort of certificate than students who didn't take any online classes. Not only are online course takers more likely to graduate, they're more likely to graduate sooner than students who don't take any online classes, Shea also found. He presented this research in a working paper at the American Education Research Association conference in Chicago in April 2015.

"It's a bit of a paradox," said Shea. "They're doing worse at the course level, but at the program level – despite lower grades – they're finishing."

I talked with Hans Johnson, a researcher at the Public Policy Institute of California, who first describedthis paradox in a May 2014 paper, "Online Learning and Student Outcomes in California's Community Colleges."

Johnson found that only 60 percent of California community students passed an online class (40 percent failed), while 70 percent of students passed a face-to-face class (30 percent failed). Yet the students who took at least some of their classes online were more likely to transfer to a four-year college or earn their associate degree. "The long-term outcomes are better for students who take online classes," Johnson confirmed.

How can this be? How can you be more likely to fail courses, but also more likely to finish your degree?

The key to understanding this paradox is inside the registrar's office.

Not everyone is failing online courses. For the 60 percent of students who are passing an online class, they're earning their way through their course requirements. Maybe they're only squeaking by with C's, and, as the research shows, they might have gotten B's in a face-to-face class. But they're racking up credits. Some of them are graduating.

And they're graduating in larger numbers than the face-to-face students because it's easier to enroll in the online classes you need. By contrast, students taking only traditional classes are having a hard time registering for classes. Budget cuts have caused many community colleges to eliminate multiple sections of courses and cut some courses entirely. For a typical community college student, who's juggling a job and a family, it can be hard to find a seat in a required class at a time that works in his or her schedule.

A student who's waiting for a traditional class to open up can wait for a long time. "The longer you're there without reaching completion, the more likely you're not going to end up finishing," explained Johnson. "If you're really motivated and intent on getting out in a timely manner, online classes are almost essential."

A small minority of community college students is very motivated. They're opportunistically taking an online course or two every semester, to stay on track and graduate. It's quite sad, actually, to think that they might've done better – and learned more – in a face-to-face class.

Statistical anomalies like this can happen in community college land, where graduation rates are very low; only 25 to 30 percent of students who start at a community college complete their degrees or transfer to a four-year school. So a small subset of motivated students can swing the graduation data in unexpected ways. In a typical high school, for example, where graduation rates are above 80 percent, an experimental writing class that leads to more failures would almost certainly cause the school's graduation rate to deteriorate, too. Even if some students are benefiting, you wouldn't see that in the school-wide data.

The question for community college leaders is whether they should continue to expand their online courses to help a small minority of students get through college as quickly as possible. It will be tempting, since those students are boosting graduation statistics. But online courses are helping the most prepared students who are most likely to succeed, not the struggling students who need the most help.