Thanks to CS for writing the following:
There has been some skepticism about the claim that 1 in 5 women is the victim of a sexual assault during college. The American Association of Universities came out with survey results from 27 schools in September 2015, which seemed to support the 1 in 5 number, but it was roundly criticized for a low response rate (19%) among other criticisms. A new survey has been released by the Bureau of Justice Statistics. It has improved questions, a much higher response rate (over 50%), and some sophisticated analyses to adjust for non-response bias. It yields nearly the same finding: 21% of women in the 9 campuses surveyed were victims of a sexual assault during college.
The actual report is here: http://www.bjs.gov/content/pub/pdf/ccsvsftr.pdf