When people talk about sexual assault on college campuses, there's one statistic that comes up again and again: one woman in five is sexually assaulted between the beginning of freshman year and graduation.
President Obama said it. So did Vice President Joe Biden. And so have many articles about campus sexual assault. That statistic, though, is far from reliable. It comes from a survey conducted at just two universities, and the researcher who led it says it was never intended to be generalized to the national level.
But it pops up over and over because, while not perfect, it's one of the few statistics we have. This hints at a disturbing truth on the issue of sexual assault: we don't really know how common it is on college campuses. We don't know how much it varies from college to college. And if we don't know either of those things, it's almost impossible to know how to stop campus sexual assault — because it's hard to measure what actually works to prevent it.
Where the 1 in 5 statistic comes from
The 1 in 5 statistic is extrapolated from a 2007 survey, the Campus Sexual Assault Study, which asked nearly 5,500 women at two large public universities about unwanted sexual contact. The study's title sounds sweeping, but Christopher Krebs, the lead researcher on the study, said in an interview that the results were never meant to apply nationwide — or even to other large public universities similar to the ones he studied.
"I think sexual assault is a phenomenon that is potentially unique at each university," he said.
The survey's origins were personal. Krebs, a researcher with the Research Triangle Institute, was teaching at a North Carolina university in the early 2000s when he heard disturbing stories from two students. Both said they had been given drugs without their knowledge and ended up in the emergency room, although neither was sexually assaulted. Krebs applied for a grant from the National Institute of Justice to study sexual assault on college campuses, hoping in part to find out how common drug-assisted sexual assault actually was.
Krebs and his colleagues picked the two universities they studied — which aren't named in the study — because administrators at those colleges were interested in participating. "It wasn't a statistical sample or a random sample or anything else," Krebs said. They reached almost 5,500 women. Nineteen percent said they had experienced either an attempted or completed sexual assault since starting college.
That figure includes all "unwanted sexual contact" — a broad category that includes not just rape and oral sex but also "forced touching" or sexual battery. That means being kissed, touched sexually, or groped against your will, even over clothing, while under the threat of force or because you are too drunk to consent.
The researchers broke down the results: since the beginning of college, 13.7 percent of women were the victim of a completed sexual assault. In all, 3.4 percent of women had been raped under the threat of force, and 8.5 percent had been raped when they were too incapacitated from drinking or drugs to consent.
"Forced touching" was, somewhat surprisingly, much less common than rape: 1.6 percent of women said they were sexually touched, but not raped, under the threat of force, and 2.6 percent said they were sexually touched but not raped when they were too incapacitated to consent.
The survey included other important findings. It asked why students hadn't reported their assaults to the police; nearly half of women raped when they were incapacitated said they felt partially responsible, and 66 percent said they didn't think it was serious enough to report. They also found freshman were more likely to be sexually assaulted than older students, and that students in Greek organizations were more likely to be assaulted than those who weren't. They found that sexual assault assisted by date rape drugs was relatively rare.
But it's the 1 in 5 figure that has really stuck — even though it didn't appear in the original report. For a later article in the Journal of American College Health, published in 2009, the researchers later used their data to estimate the likelihood that women would experience sexual assault by graduation. That likelihood was about 19 percent — one in five.
What other national surveys have found
At the same time Krebs and his colleagues were surveying students at two public universities, the Medical University of South Carolina was taking on a bigger project, also funded by the National Institute of Justice: a national survey of how common rape is during a woman's lifetime. As in Krebs' study, researchers were particularly interested in the role of date rape drugs.
Researchers surveyed a sample of 2,000 women from more than 200 colleges. Unlike Krebs' study, they only asked about experiences that could be legally classified as rape — in other words, involving penetration. They found 13 percent of college women had been raped either before they entered college or while they were enrolled. They estimated nearly 5 percent of college women were raped annually, about 300,000 students per year.
"In terms of being able to generalize the findings out nationally, I think it remains probably the best data we have now," says Dean Kilpatrick, a professor at MUSC who directed the study.
One key finding, Kilpatrick said, was that the risk of mental health problems after a rape was just as large for women who were incapacitated when they were raped as for those who were raped by force.
But college women who were raped while they were too drunk or drugged to consent were less likely to describe what happened to them as rape. More than two-thirds described it either as "unpleasant but not a crime," or as "a crime, but not rape."
Why we don't know more, and why it matters
There's a reason Krebs' and Kilpatrick's studies are the most frequently cited; despite their flaws, they're what we have. (There is one other nationally representative survey on sexual crimes against college women, but it's from 2000 — now very out of date. And new data from the National Crime Victimization Survey doesn't ask about specifically about incidents where people were too intoxicated to consent.) Funding for national-level research on campus rape has historically been scarce. And colleges themselves are reluctant to research sexual assault and publish the results: just 16 percent of colleges conduct regular surveys about sexual assault, according to a recent Senate report.
This lack of campus-level research makes it more difficult to understand the scope of the sexual assault problem. It also means it's difficult to compare colleges to figure out which risk factors make sexual assault more likely and which interventions might help get it under control.
It makes sense that a college where most students live on campus, and where there are prominent sports programs and Greek life, might have different risk factors than a college where most students commute or aren't in their late teens and early 20s. But even superficially similar universities can be very different in crucial factors like students' attitudes about women or trust in university staff, Krebs says. That's why it's important to have data on many different colleges — to figure out if those factors matter as much as people believe they do.
We could be about to get much more data on campus sexual assault
Colleges, understandably, don't like the idea of making sexual assault data public. "The fact that a substantial proportion of your college students have been victims of rape is not something high on the list of things that [colleges] put on their website," Kilpatrick said. "There’s a lot of denial that goes on."
But the recent publicity surrounding campus sexual assault has led to an interest in better data. Krebs says he and colleagues developing a new version of the 2007 survey, funded by the Bureau of Justice Statistics and the Office on Violence Against Women. "A number of campuses" are interested in administering it, he says.
The Association of American Universities, a group of 60 prestigious research universities, is developing a voluntary survey with Westat Research, another research firm. But only aggregated data will be released — not information about individual colleges. That's caused some concern among sexual assault experts, who argue that researchers who work in this field should be more involved in designing the study, and that colleges should release their own data so that they can be compared to one another. (The AAU is encouraging colleges to do so, spokesman Barry Toiv said in an email to Vox.)
Comparisons like that would be very useful, Kilpatrick said, although he added that he understands why colleges might not be eager to be compared on their rape statistics.
Congress, though, might make them do it. Proposed legislation require annual surveys at every college about sexual assault and the campus environment. The results of those surveys would be made public.
Correction: An earlier version of this article misstated who was included in Krebs' survey. It included students at all grade levels.