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Power of testing proportions in small two‐sample studies when sample sizes are equal
Author(s) -
Davis Alan B.
Publication year - 1993
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780120806
Subject(s) - sample size determination , statistics , type i and type ii errors , power (physics) , power function , exact test , mathematics , sample (material) , power analysis , chi square test , function (biology) , statistical power , computer science , algorithm , physics , mathematical analysis , quantum mechanics , evolutionary biology , cryptography , biology , thermodynamics
In planning experiments having two groups of equal but small size, investigators face the uncertainty of power calculations that rely on asymptotic methods. This paper presents a method for determining power for two‐sided tests. I compare two randomization tests, Fisher's exact test (FET), and the mid‐ P (MID), with the uncorrected chi‐square test (CHI). Results show power as a function of relative risk for these methods, and assesses their relative power and type I error rates. MID is shown to have intermediate power between CHI, which is the most powerful, and FET, the least powerful. Situations are shown in which CHI and MID occasionally exceed the nominal level of α.