Some advantages of permutation tests

There are two especially useful models of statistical inference, although only one, the normal curve model, is universally taught. The less well known permutation model is contrasted with the normal model and the case made that the permutation model is often more appropriate for the analysis of psychological data. Inappropriate interpretations generated by teaching only the normal model are illustrated. It is recommended that both models be taught so that students and applied workers have a better chance both of understanding the nature of the hypothesis that is being tested, and of correctly discriminating the statistical conditions that support causal inference and generality inference.