Thanks for that @AndyW. I can't vote for closing yet, so I'll just watch that space (but I support a close). Yes, I assumed DFA would need an expert, this sort of thing shows that we aren't quite there yet in terms of having enough stats experts on the site. I think we should leave it open in the hope that one day an expert arrives (and in the meantime I might try FIND an expert and ask them :-) )

@chl's comment on this question seems like a good enough answer to me, it even has upvotes, so I CW'd it, if anyone agrees give it a vote.