increase in size when in people that do smoke. whenever you look at people doing what they normally do, there could be other differences. there was some evidence they might drink more alcohol than the other group. so you cannot say for sure it is marijuana, but the reality is you cannot do that type of perfect study because of ethical reasons. the perfect way would be randomly assign people saying you will smoke and you will n : not.not: but there are issues with that because if we think it is harmful we cannot make people smoke it. >> you look at alcohol and cigarettes and syntax and two states that made this drug that is more dangerous that many thought legal. what do you think about that? >> i think there is a difference