title: Paired versus two-sample design for a clinical trial of treatments with dichotomous outcome: power considerations.
abstract: For the same number of observations in a small-sample clinical trial with dichotomous outcome, the statistical power associated with a two-sample design, analyzed by Fisher's exact test, is slightly greater than that associated with a matched design, analyzed by McNemar's test, and hence of the matched design, is monotone increasing in the within-pair correlation between the treatment responses. Power curves are presented which demonstrate that positive within-pair correlation, even when quite small, can result in a superiority in power for the matched design. Conversely, in the rare situations where there is a negative within-pair correlation, choice of a two-sample design can result in a substantial gain in power.
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D008954:Models, Biological; D011336:Probability; D012107:Research Design; D013223:Statistics as Topic