Could Student-Athlete's Demanding Schedules Be Affecting Their GPA?

A recent study at Kalamazoo College shows that Student-Athletes, on average, have a lower GPA than Non Student-Athletes, even though both groups rate their Academic Effort equally on a scale of 1-5. On average each group spends about the same amount of time studying, roughly 14 hours and 30 minutes per week(2 hours 4 minutes per day), and each group also has about same amount of free time, roughly 13 hours and 30 minutes(1 hour 56 minutes per day), per week.
Since both groups put forth the same amount of effort but have different outcomes, this simply means that if Student-Athletes want to disprove the statistics, they are going to have to expend more effort on their academics than their Non Student-Athlete peers do. Since it is not in the control of Student-Athletes to shorten their time at practice (roughly between 12 hours 47 minutes and 14 hours 50 minutes per week) Student-Athletes are going to have to sacrifice some of the little free time they have in order to do so. Student-Athletes have the choice to sacrifice their free time or not, but if they do it might be possible to improve their GPA enough to surpass their Non Student-Athlete peers. Will this happen? We will have to wait and see.

The study of 101 students at Kalamazoo College, 62 of them being Student Athletes and 39 of them being Non Student-Athletes, shows the following:

Student-Athletes | Non Student-Athletes

GPA: 3.15-3.33 | 3.27-3.49

Study Time/Week: 12:40-16:32 | 10:42-17:58

Free Time/Week: 9:04-16:45 | 11:06-17:07