[Alex3917]

"I really don't think you can adjust away the teenage propensity to lie on these sorts of things."

The research seems to show that the self-reported responses are pretty accurate. For example, the number of people who reported using LSD basically went to zero right after the Pickard bust in 2003, when pretty much the entire US production got shut down. This means that if there are people lying about taking drugs they haven't been taking, it can't really be much than a couple tenths of a percent.