Research consistently shows that the majority of rape and other sexual assault victims do not report their attacks to law enforcement. Reasons for not reporting include fear of reprisal, shame, uncertainty about whether a crime was committed, or a belief that an incident was not sufficiently serious enough to report. As a result, researchers generally rely on surveys to measure sexual violence that is not reported to the police. Estimates of campus sexual assault measured on surveys vary across populations and over time, however a recent review concluded that a "reasonable average" of around 1 in 5 (20%) of women were sexually assaulted during their time in college. And although much of the research on sexual assault has focused on college campuses, there is evidence that non-students of t