Fast and accurate computation of the exact confidence limits for the common odds ratio in several 2 x 2 tables

Mehta, Patel, and Gray proposed a network algorithm for the exact confidence limits of the common odds ratio in several 2x2 tables. Their algorithm was implemented in the StatXact and Egret statistical packages and further discussed by Vollset, Hirji, and Elashoff. The need to evaluate polynomials of potentially very high degrees, however, poses some numerical difficulties. This article presents a method that cuts the degree of polynomials by at least one half. Two other modifications to further stabilize and speed the computation are also proposed.