Many of the channels for digital revenue, DLC and F2P in particular I believe, try to attract
whales, people who spend far above what the average player spends. I first heard of the phenomenon from a friend who worked behind the scenes at a social gaming company. He told me that 1% of the players more than subsidized the free experience for the other 99%, because the 1% spent such inordinate amounts of money on non-free extras. Recently there was
this thread about a presentation on how Kongregate (owned by GameStop) works behind the scenes. See page 12, in particular of that PPT:Anyway, if you have a tiny percentage of players who actually spend money, then a survey will have to be very good to capture that dynamic.