The GSR, or graduation success rate, as calculated and used by the NCAA is slightly different than the graduation rate published by schools because of the way they account for transfers and kids who remain in good standing. I will leave it to the stats people among us, but that may account for the difference between the 97 and 98 percent rates.
The real question is the relative rates. Do athletes graduate at a rate that is statistically significantly different than non athletes? I don’t care so much about whether it is a four or five year rate, because athletes often take a year off from school because of injury so they can compete for four years. This is because the Ivy only permits full time undergraduates to compete in varsity athletics.