Town of 2000 people (half men, half women) - so the one in four figure for women gives you 250 women.
Let's take Lisak's figure down to 5% i.e. one in 20, so 50 rapists. 6 rapes each - that's 300 rapes, closer to 1 woman in 3 (hence my comment about some women being unfortunate enough to be raped twice). Yes, the figures do work, once one realises that it is women, i.e. half the population, to whom the 1 in 4 figure applies. My point is that the figures look ball-park the same whether you arrive at them by counting up what women say about their experiences, or what men are prepared to disclose about their actions - so you have two independent research methodologies giving broadly the same answer as to the prevalence of rape in the population.
NPR article on campus rape
He [Lisak] found them by, over a 20-year period, asking some 2,000 men in college questions like this: "Have you ever had sexual intercourse with someone, even though they did not want to, because they were too intoxicated [on alcohol or drugs] to resist your sexual advances?"
Or: "Have you ever had sexual intercourse with an adult when they didn't want to because you used physical force [twisting their arm, holding them down, etc.] if they didn't cooperate?"
About 1 in 16 men answered "yes" to these or similar questions.
Profile Of A Rapist
It might seem like it would be hard for a researcher to get these men to admit to something that fits the definition of rape. But Lisak says it's not. "They are very forthcoming," he says. "In fact, they are eager to talk about their experiences. They're quite narcissistic as a group — the offenders — and they view this as an opportunity, essentially, to brag."