The progress of the betting in a baseball game

The development of the Internet has led to the creation of countless new markets, among them, online, in-game betting markets for sporting contests. We examine the behavior of prices as events unfold in a baseball game. Specifically, we compare the evolution of prices during a game with probability estimates generated by an empirical model of scoring in baseball. We find that price changes correspond closely to changes in the probability of winning, for plays of both small and dramatic impact. Nevertheless, data limitations inhibit the ability to make strong claims regarding the hypothesis of efficient pricing.