California State University at Long Beach. (Joe Philipson/CSULB)

There were no rapes reported in 2014 at California State University at Long Beach, a public university with about 36,000 students. That could seem like a positive sign. But school officials aren’t boasting about it. They know sexual violence victims are often reluctant to step forward, and they want to hear more often from survivors.

“We always operate under the assumption that zero does not really mean zero,” said Cal State Long Beach spokesman Mike Uhlenkamp. “We realize that under-reporting will happen. It is a fact based on the national data. We’re going to try to do what we can to change that culture on our campus.”

A Washington Post review of federal campus safety data for more than 2,200 colleges that offer bachelor’s or advanced degrees found that more than 1,300 of the schools had no reports of rape on campus in 2014, the most recent year for which data is available.

[See a table, below, of the schools that had zero rape reports]

The numbers underscore what is often a huge gulf between the estimated prevalence of sexual violence on campus and the actual number of reports schools receive. A Post-Kaiser Family Foundation poll last year found that one in five young women who attended college in a four-year span said they had been sexually assaulted during that time — a finding echoed in other surveys. But a far smaller share said they reported such incidents to school authorities.

“It’s a harsh reality that a lot of parents and others in society don’t want to deal with: Sexual violence is on every campus,” said Laura L. Dunn, founder and executive director of the advocacy group SurvJustice. “Any time you have a zero, it is not an indicator of safety. It is an indicator of comfort in reporting.”

Sen. Kirsten Gillibrand (D-N.Y.) said there are two explanations for why schools would have no rape reports: “Either they don’t have an adequate reporting system … or they know about the rapes and are putting them under the rug.”

Others say the extent of campus sexual assault has been overhyped. In an opinion piece this month in The Post, KC Johnson, a professor at Brooklyn College and the CUNY Graduate Center, and Stuart Taylor Jr., a scholar at the Brookings Institution, lamented “a myth that our universities are mired in an epidemic of sexual violence.” Johnson and Taylor wrote that campus activists, the Obama administration and many in the media have used “discredited surveys” to claim there are hundreds of thousands of campus sexual assaults annually.

The Post analyzed what public institutions and nonprofit private colleges of all sizes disclose to the federal government under Clery Act requirements. Data released in December show for the first time the total number of reports per school specifically for rape. Previously, rape had been grouped together with other crimes in a category called “forcible sex offenses.”

Some schools had dozens of reports of rape in 2014. There were 43 each on the main campuses of Brown University and the University of Connecticut, the highest totals that year for main campuses at schools The Post analyzed. There were 26 reports of rape at Stanford and four reports at Baylor, two universities at the center of sexual assault controversies in recent weeks.

“When more are reported, we have to see that as a good thing initially,” said Sen. Claire McCaskill (D-Mo.). “Ideally, you want reports going up and incidents going down.”

The federal data reflect just reports — not criminal charges, prosecutions or formal student misconduct complaints — of incidents matching the FBI definition of rape in the Uniform Crime Reporting program: “Penetration, no matter how slight, of the vagina or anus with any body part or object, or oral penetration by a sex organ of another person, without the consent of the victim.”

Some schools with zero rape reports have special circumstances. Those that operate largely or wholly online, such as Western Governors University (57,800 students), the University of Maryland University College (47,900) and Excelsior College (41,500), are much less likely to receive crime reports of any type than schools with traditional campuses. Medical, health and law schools also appear to have lower reporting rates.

With 66,000 students, Miami Dade College was the largest four-year school to have zero rape reports. But it is a commuter school, with no student dormitories, and produces far more associate’s than bachelor’s degrees. All of those factors set it apart from traditional residential colleges.

“The low number in our annual Clery Act reports is a reflection of the positive atmosphere at our institution,” said Miami Dade spokesman Juan C. Mendieta. “It not a reflection of hesitation by our students to report an incident.”

Some of the schools with zero rape reports on campus were seminaries or religious institutions with tiny enrollment.

Of approximately 2,000 schools analyzed with at least 200 students, a little more than half had zero rape reports. Among them was the public University of Louisville, with about 21,500 students.

“We wouldn’t want to speculate on whether or not there are unreported sexual assaults on our campus,” Louisville spokesman John R. Karman III said when asked about the data. “The number — zero — accurately reflects what was reported to university police in 2014.”

Here is a table listing, by size, schools with zero rape reports on campus in 2014 and at least 200 students. This analysis, unlike one The Post published last week, includes data from satellite campuses as well as hybrid schools like Miami Dade that offer two-year and four-year degrees. It excludes for-profit colleges and community colleges that do not offer bachelor’s degrees. You can also see the chart by clicking here.

Zero rape reports