>how representative are those people of the population at large?

Another question is whether people truly understand their privacy exposure? They know FB has some information on them because they submit it, but they don't know how much info in total (sites visited, location tracking, etc), how that data is combined/used, who has access to it, etc.

And, they assume that whatever FB is doing with their data must be OK/legal because laws.

I think that's what we saw with reactions to these recent revelations. When an inkling of the real privacy exposure surfaced, people freaked.

And the follow-up question is, how much do they think it's important relative to other things?