One campus rape is one too many. But the severe new policies championed by the White House, the Department of Education, and members of Congress are responding to the idea that colleges are in the grips of an epidemic—and the studies suggesting this epidemic don’t hold up to scrutiny. Bad policy is being made on the back of problematic research, and will continue to be unless we bring some healthy skepticism to the hard work of putting a number on the prevalence of campus rape.

That finding diverges wildly from the notion that one in five women college women will be sexually assaulted by the time they graduate. That’s the number most often used to suggest there is overwhelming sexual violence on America’s college campuses. It comes from a 2007 study funded by the National Institute of Justice, called the Campus Sexual Assault Study, or CSA. (I cited it last year in a story on campus drinking and sexual assault.) The study asked 5,466 female college students at two public universities, one in the Midwest and one in the South, to answer an online survey about their experiences with sexual assault. The survey defined sexual assault as everything from nonconsensual sexual intercourse to such unwanted activities as “forced kissing,” “fondling,” and “rubbing up against you in a sexual way, even if it is over your clothes.”

There are approximately 12 million female college students in the U.S. (There are about 9 million males.) I asked the lead author of the study, Christopher Krebs, whether the CSA represents the experience of those millions of female students. His answer was unequivocal: “We don’t think one in five is a nationally representative statistic.” It couldn’t be, he said, because his team sampled only two schools. “In no way does that make our results nationally representative,” Krebs said. And yet President Obama used this number to make the case for his sweeping changes in national policy.