Cheating at Professional Bridge
Interesting article on detecting cheaters in professional bridge using big-data analysis.
Basically, a big part of the game is the communication of information between the partners. But only certain communications channels are permitted. Cheating involves partners sending secret signals to each other.
The results of this can be detected by analyzing lots of games the partners play. If they consistently make plays that should turn out badly based on the information they should know, but end up turning out well given the actual distribution of the cards, then we know that some sort of secret signaling is involved.