Humans are notoriously bad at estimating risk. Most people fear flying far more than driving, even though the odds of dying in a car accident (1 in 107 in the US, for example) are far higher than perishing in an aircraft crash (about 1 in 11 million). What we are really good at, however, is self-deception. Take smoking. By now, just about everyone must surely know that tobacco is extremely bad for us in all