Who are the most effective fans in college basketball — and which fans aren’t effective at all?

Part of the appeal of college basketball is the creative and spirited fans who do everything in their power to rattle the visiting team, especially during free throws. Duke has the Cameron Crazies. Michigan State has The Izzone. And the most inventive fans — and the single most effective in the country — appear to be the ones who deploy the so-called Curtain of Distraction at Arizona State, which The Upshot covered in detail last month.

Fans are so central to the college basketball experience that they’re often called the sixth man. What has long been unclear is whether this sixth man was actually helping the home team, or whether opposing players were focused enough to shut out rowdy distractions.

And so we analyzed free-throw data over the past five seasons, comparing the free-throw percentages of visiting teams in hundreds of Division I arenas in men’s college basketball. We focus on free throws because this is when the sixth man is arguably the only relevant defensive player.