As I've learned at a market research class at university, the main difference from actual scientific surveys with properly constructed and weighed population samples is that in market research, you can weigh the results however the hell you want until it kind of looks presentable at a management meeting. Any and all questions about what weighs you should apply, what to throw out, etc. can and should be answered with "that depends." Yeah, the professor (an external lecturer working at a big market research firm) might have been a bit more cynical than needed. But the point is, as the sample is not really representative, they will have to choose what scores and opinions to concentrate on for themselves.