Classi cation by Pairwise Coupling

We discuss a strategy for polychotomous classi cation that involves estimating class probabilities for each pair of classes and then cou pling the estimates together The coupling model is similar to the Bradley Terry method for paired comparisons We study the na ture of the class probability estimates that arise and examine the performance of the procedure in real and simulated datasets Clas si ers used include linear discriminants nearest neighbors and the support vector machine