Advanced SearchSearch Tips
The Comparison of the Unconditional and Conditional Exact Power of Fisher`s Exact Tes
facebook(new window)  Pirnt(new window) E-mail(new window) Excel Download
 Title & Authors
The Comparison of the Unconditional and Conditional Exact Power of Fisher`s Exact Tes
Kang, Seung-Ho; Park, Yoon-Soo;
  PDF(new window)
Since Fisher`s exact test is conducted conditional on the observed value of the margin, there are two kinds of the exact power, the conditional and the unconditional exact power. The conditional exact power is computed at a given value of the margin whereas the unconditional exact power is calculated by incorporating the uncertainty of the margin. Although the sample size is determined based on the unconditional exact power, the actual power which Fisher`s exact test has is the conditional power after the experiment is finished. This paper investigates differences between the conditional and unconditional exact power Fisher`s exact test. We conclude that such discrepancy is a disadvantage of Fisher`s exact test.
Conditional test;sample size determination;homogeneity;binomial;
 Cited by
Berger, R. L. and Boos, D. D. (1994). P-values maximized over a confidence set for the nuisance parameter, Journal of the American Statistical Association, 89, 1012-1016. crossref(new window)

Crans, G. G. and Shuster, J. J. (2008). How conservative is Fisher's exact test? A quantitative evaluation of the two-sample comparative binomial trial, Statistics in Medicine, 27, 3598-3611. crossref(new window)

Cytel (2006). StatXact, version 6.0, Software for Exact Nonparametric Statistical Inference with Continuous or Categorical Data, Cytel Software: Cambridge, MA.

Gail, M. and Gart, J. J. (1973). The determination of sample sizes for use with the exact conditional test in $22{\times}2$ comparative trials, Biometrics, 29, 441-448. crossref(new window)

Haseman, J. K. (1978). Exact sample sizes for the use with the Fisher-Irwin test for $2{\times}2$ tables, Biometrics, 34, 106-109. crossref(new window)

Kang, S. H. and Ahn, C. W. (2008). Tests for homogeneity of two binomial proportions in extremely unbalanced $2{\times}2$ contingency tables, Statistics in Medicine, 27, 2524-2535. crossref(new window)

Lydersen, S., Fagerland, M. W. and Laake, P. (2009). Recommended tests for association in $2{\times}2$ tables, Statistics in Medicine, 28, 1159-1175. crossref(new window)

Lydersen, S. and Laake, P. (2003). Power comparison of two-sided exact tests for association in $2{\times}2$ contingency tables using standard, mid p, and randomized test versions, Statistics in Medicine, 22, 3859-3871. crossref(new window)

Martin Andres, A., Quevedo, M. J. S. and Mato, A. S. (1998). Fisher's mid-P-value arrangement in $2{\times}2$ comparative trials, Computational Statistics and Data Analysis, 29, 107-115. crossref(new window)

Martin Andres, A., Silva Mato, A., Tapia Garcia, J. M. and Sanches Quevedo, M. J. (2004). Comparing the asymptotic power of exact tests in $2{\times}2$ tables, Computational Statistics and Data Analysis, 47, 745-756. crossref(new window)

Sahai, H. and Khurshid, A. (1996). Formulae and tables for the determination of sample sizes and power in clinical trials for testing differences in proportions for the two-sample design: A review, Statistics in Medicine, 15, 1-21. crossref(new window)

Suissa, S. and Shuster, J. J. (1985). Exact unconditional sample sizes for the $2{\times}2$ binomial trial, Journal of the Royal Statistical Society, Series A, 148, 317-327. crossref(new window)