Our Crime Grades are generated using data from college campuses as well as data from the FBI. 

The crime score is generated based on the scores of all the other schools in the system. College campuses generally have fairly low amounts of reported crime, which is why a school may appear to have a poor grade while still not having a lot of crime.

In addition, just because a school has a higher than average crime rating does not necessarily mean that it is less safe than other schools. A higher rate of reported crime may simply mean the school does a better job of enforcing rules and has more security on campus.

Read more here: http://inside.collegefactual.com/methodologies/about-our-crime-ratings