and tamara mcleod, an athletic trainer who works with schools and researches concussions. she's with a.t. still university in arizona and was a reviewer of today's report. robert graham, i want to start with you and pick up on just this question of what is and isn't known. we know that concussions are important events. what do we know about the long-term effects, especially, when it comes to young people? >> well, i think to pick up on the doctor's comment as we came into this conversation, you might say we know an increasing amount about the numerator. we know more and more about the incidents of how many concussions are reported in different sports and different agents. what we don't snow the denominator. we don't know whether or not we're getting all of the reports and specifically research needs to be taken on a longitudinal basis. if something happens to somebody at the age of seven, what are the implications at the age of ten? at the age 2061? we don't have any of that. >> this ha s because there hasn't been attention paid to children at this age? >> i think what we'