It's boringly common for rape prevention activists to claim that false accusations are so rare that we should assume accusations are true, even to the point of making accused rapists social pariahs when they haven't been convicted of a crime.
So here comes Scott Greenfield with a big dose of problem for that narrative: it's unproven, and by its very nature, almost impossible to prove. He links to Jack Chin, who cites even more people:
A widely cited review of the literature suggests that a more accurate conclusion of reliable studies is between 2 and 10%. But CUNY Dean Michelle Anderson published an article the conclusion of which on this point seems solid to me: "In fact, there is no good empirical data on false rape complaints either historically or currently . . . As a scientific matter, the frequency of false rape complaints to police or other legal authorities remains unknown." A more recent National District Attorney's Association study reviewing the same literature, while debunking absurdly high estimates from some unreliable studies, agreed: "Of course, in reality, no one knows—and in fact no one can possibly know—exactly how many sexual assault reports are false." We (and by this I mean the public at large, people involved in the educational system, and the legal community of prosecutors, defenders and judges) rarely know the accused or the complainant and never know the truth; we can only make decisions based on the evidence in the particular cases. There is no rule of thumb to rescue us from that situation of uncertainty.
Well then, let those reports be cited every time a rapid activist tells us that false rape accusations are so rare that we behave as if they don't exist, and that questioning a self-described victim's story is an evil act on par with committing a rape.