200 kids from 6 schools in 1 area and they only really talked to 11 of them not the greatest sample ever didnt work like that for me anyway, im not a smoker and i've smoked a cigarette a couple of times
I think you may be interpreting the story wrong. I believe it means that they interviewed each student 11 times.
Bit like any other drug then. Part neurochemical effect, part autosuggestive priming. An addiction is born.