OkCupid's team often publish interesting studies, based on the tests they provide to their users. The last I read, "The best questions for a first date", finds some funny correlations. E.g. between the probability of having sex on a first date, and liking the taste of beer! It's simple statistics, but the charts are provided as a proof.
http://blog.okcupid.com/index.php/the-best-questions-for-fir...