ie, two girls sit in the same sex ed class, one gets pregnant and the other doesn't. how can you say that the sex ed did or did not play a factor in the one girl not getting pregnant?
a more telling survey would be to break the study down by race/culture. what is the teen pregnancy rate among whites in Vermont compared to the teen pregnancy rate for whites in Texas? break the study down according to race and you can take the race factor out of the equation and produce a more focused reliable study. or break it down by socio economic grouping. anything to reduce/eliminate variables.
but they won't do that because they are afraid the results will show that regardless of the sex ed classes they get minorities and low socio-economic groups will have a higher rate of teen pregnancy..and god forbid we can't admit that. better to stick our heads in the sand and blame "abstinence based sex ed".