Andrew Robson Articles on Finessing
If one opponent plays a critical card in a suit, his partner is twice as likely to have the adjacent card in the same suit. This is because of the Principle of Restricted Choice (“PRC”) - a mathematical theory that was found to have relevance at the bridge table by Terence Reese. He first expounded the theory in his epic book “The Expert Game”, written in 1958 - an inspirational read for any ambitious player.
If you need convincing, watch this 'Monty Hall' Video.