Personally I think the Bristol guys have too much time on their hands, and that there are better ways to spend one's time than drawing up dozens of hypothetical formulae to describe a phenomenon that can be explained in one sentence as: Some customers tip; the researchers like it; there's not really any downside.
But it's an interesting insight into the minds of the people who work for the University of Bristol's Centre for Market and Public Organisation. Is Google Answers a market that needs to be organised? Isn't an “organised market” a contradiction in terms anyway?
Here's a taste, in case you've not yet been tempted to click:
(Thanks to hedgie-ga for bringing this to my attention.)