A New Probability Model for Determining Exact P-Values for 2 x 2 Contingency Tables When Comparing Binomial Proportions

Abstract

A new probability model to determine exact P-values for 2 .times. 2 contingency tables and its computerized solution are described. This model can be used in place of Fisher''s "exact test" when analyzing contingency tables that compare binomial proportions estimated from samples of larger populations. The model accomodates different levels of a priori information about the underlying probability of success. The computerized solution is interactive, written in Pascal, and specifically designed to run on small desktop microcomputers. Applications of the probability model to behavioral and evolutionary data are describe.