The United Nations Security Council recently mandated the collection of data on sexual violence around the world, which should be good news for anti-rape activists and policymakers. But Amelia Hoover Green isn’t so sure.

Hoover Green is an assistant professor in the Department of Politics in the College of Arts and Sciences who studies rape and sexual violence reporting and statistics. Much of her work and her writing centers on how and why policymakers should improve sexual violence data collection in conflicted and post-conflict countries.

She says that while it’s good that sexual violence and rape have entered the global conversation, there is good data, and there is bad data. And bad data can be very harmful to efforts to create effective rape prevention policies.

Good data is representative data collected via systematic samples like surveys, for example. Bad data, or “convenience data,” is gathered unsystematically from self-report sources like police or hospital records.

“It is absolutely a good thing,” she says of the UN’s new data collection mandate, “except that, by and large, when the UN says ‘data’ they implicitly mean ‘numbers.’ But we don’t usually understand the origins of these numbers, so we end up with ostensibly numerically backed claims based on data that are just not accurate.”