medication. you wouldn't conclude that medicatiobefore taking medicatie people weren't sick. u need a group of subjects. some of them get the program or medication. some do not, and then you follow them over time. unless you do a scientifically valid control study, you're not entitled to conclude that a program does or doesn't work. it's very important principle of scientific methodology that applies to medical research. >> do you agree with that? >> yes, i agree with the doctor's comments. that is a huge limitation of my research. this is date abou database spond collected by the u.s. department of health and human services at 195 different schools. however, if we think the main principles and the core goals of every single anti-bullying program is preventing, removing the bullying problem from the school, even if they have all different types of education and curriculum, procedures, we can assume that they share the common goals. if this is true we have to get, even though we're asking whether you have a program or not, even though we're asking just binary, we are expecting