Dr. McKee, the study's author, acknowledged that and addressed it:

> But 110 positives remain significant scientific evidence of an N.F.L. player’s risk of developing C.T.E., which can be diagnosed only after death. About 1,300 former players have died since the B.U. group began examining brains. So even if every one of the other 1,200 players had tested negative — which even the heartiest skeptics would agree could not possibly be the case — the minimum C.T.E. prevalence would be close to 9 percent, vastly higher than in the general population.