links for 2010-05-31

Imagine this card trick. A statistician divides a regular deck of cards into two sets: one of 20 and one of 32 cards. Next, he urges two groups of students to investigate the cards, and hands out one set of cards to each of the groups. Both groups start counting the cards, and cross-tabulating the numbers based on several ways they can come up with. [...] This must be magic: in the complete deck of cards no association is present, while in the two subsets of cards a positive association is found."