Friday the 13th

(An oldie but goodie.) The British Medical Journal published an article about the connection between Friday the 13th superstitions and health. They conducted separate t-tests comparing number of shoppers in supermarkets, and number of drivers on the highway on Fridays the 13th and ordinary Fridays to gauge superstition. (Are people staying in on these days?) They also compared rates of traffic fatalites on the two kinds of Fridays.