Which ball is the roundest? A suggested stability index for tournaments

Journal article, 2006

All sports have components of randomness that cause the "best" individual or team not to win every game. According to many spectators this uncertainty is part of the charm when following a competition or a match. Have different sports more or less of this unpredictability? We suggest here a general measure, a tournament stability index, together with its associated p-value which we denote the "coin-tossing-index." These indexes are aimed to quantify the randomness factor for different tournaments, and different sports. As an illustration we exemplify and discuss these measures for basketball, squash, and soccer. Some additional results will also be given on a few tournaments in ice-hockey, and handball. Furthermore, we discuss a couple of combinatorial optimization questions that turned up on the way.