One has to wonder about a study in which over 25% of college-aged men were unable to achieve an erection.
When I was college-aged, I was often unable to get rid of an erection.
I think two different conclusions might be drawn. These volunteers were recruited at a night club during spring break. Were many of them so drunk they couldn’t get it up? If so, alcohol may have actually biased the recorded measurements by lowering the averages due to decreased EQ.
Another conclusion might be that a bunch of guys volunteered under peer pressure when a group of guys was approached. Those who might have felt that they would “come up short” might have used this convenient excuse to opt out of the measurement process. That would, of course, have biased the averages in the other direction.
Maybe both phenomena were in play. One has to assume some sort of bias, however, in a sample of young men in which the incidence of impotence was this high.