Last December, Rolling Stone published a now-infamous story that seemed to confirm every parent’s worst fears about sexual assault on college campuses.

Within months it had been discredited and retracted, making it hard to argue with those who believe the campus rape problem is overblown, even fabricated.

The too-bad-to-be-true story of a gang rape at a University of Virginia frat house — and the indifferent response attributed to college administrators — was a big setback to an important national conversation. What’s really behind what has come to be called the “rape culture” on American college campuses?

And what needs to be done about it?

So we welcome the release this week of a massive survey conducted by the Association of American Universities. More than 150,000 students at 27 schools participated, making it one of the largest-ever studies of campus sexual violence.

The study offers a nuanced view of what’s happening on campuses across the country, and no, it’s not just a lot of irresponsible drunken sex followed by morning-after regret.

Overall, 23 percent of undergraduate women who participated in the survey said they’d experienced unwanted sexual contact since enrolling at the school, either through physical force or because they were incapacitated. The authors acknowledged that that doesn’t necessarily reflect the overall rate of unwanted contact, since those who chose not to complete the survey were less likely to have been victims.

The questions on the AAU’s survey drilled down in ways that earlier surveys did not, producing a more detailed picture of the victims, the circumstances of those unwanted encounters and the campus climate in which they occurred.

Overall, 11 percent of undergraduate women said they’d had unwanted sexual contact under those circumstances.

Some findings that might (or might not) surprise you:

• Men are victims, too: Overall, 5 percent of undergraduate males reported nonconsensual sexual contact since enrolling at their school.
• Those who identified as transgender, genderqueer or nonconforming experienced higher rates for all types of unwanted encounters.
• Freshmen are most at risk. The incidence of unwanted contact declines with each year.
• Most encounters weren’t reported. Only 25 percent of students who experienced forced penetration reported it, and only 13 percent of those who were incapacitated by drugs or alcohol.
• Even more disturbing: 44 percent of those surveyed said they’d witnessed an incapacitated person headed for a sexual encounter. Three out of 4 did nothing to stop it.

Among the 27 universities that participated, there were wide variations in the type and frequency of unwanted encounters, and in students’ perception of the threat on campus and how much they trust school officials to deal with it.

Some schools have a bigger problem; some are doing a better job than others.

For individual schools, the findings offer a truly useful look at what’s happening on their campuses and how well they’re handling it. The researchers say they’ll make their survey materials available to any school that wants to use them. It’s an offer any college would be wise to accept.