emily schmall is a member of the a.p. team. she joins me now from dallas. thanking for joining us. key point you're making is that this happens more often than we know, right? is it possible to say how pervasive it is? >> yes, it's absolutely true. it happens far more often, i think, than people realize. to say exactly how pervasive it is, it's difficult though. because just like rape and sexual assault perpetrated in other places, rape and sexual assault in schools is definitely underreported. so while we have been able to tally about $17,000 incidents over the four years, experts have told us it's just the tip of the ice bherg. >> let's establish what we are talking about. really, we're going beyond bullying, beyond hazing. tell us what you are looking at exactly. >> yes. so we were very, very deliberate in what we counted. and we are looking at sexual assault as defined by the justice department which means forced intercourse ored so omee-- sodomy. forced oral sex, the most severe forms of sexual assault. we deliberately did not include categories like sexual harassment or bully