More Powerful Tests from Confidence Interval p Values

In this article, the problem of comparing two independent binomial populations is considered. It is shown that the test based on the confidence interval p value of Berger and Boos (1994) often is uniformly more powerful than the standard unconditional test. This test also requires less computational time. KEY WORDS: Binomial, Confidence interval, Contingency table, Homogeneity test, Independence, P value, 2 \Θ 2 table. 1 INTRODUCTION The problem of comparing two binomial proportions has been considered for many years. The most commonly used test is Fisher's Exact Test (Fisher, 1935), a conditional test. Barnard(1945, 1947) proposed an unconditional test for this problem. Although unconditional tests are usually more powerful than conditional tests, they are computationally much more complex. But recent advances in computing have made unconditional tests practical, and they are beginning to appear in statistical software packages such as StatXact 3 for Windows. In this article it i...