title: Choice of test for association in small sample unordered r x c tables.
abstract: Pearson's chi-squared, the likelihood-ratio, and Fisher-Freeman-Halton's test statistics are often used to test the association of unordered r x c tables. Asymptotical, exact conditional, or exact conditional with mid-p adjustment methods are commonly used to compute the p-value. We have compared test power and significance level for these test statistics and p-value calculations in small sample r x c tables, mostly 3 x 2 and some with both r and c are greater than 2. After extensive simulations, in general we recommend using an exact conditional mid-p test with Pearson's chi-squared or Fisher-Freeman-Halton's statistic, which usually is the most powerful test yet preserve the approximate significance level. Moreover, we recommend that the asymptotic Pearson's chi-squared or other asymptotic tests not be used for small sample r x c tables.
authors.affiliation: Unit for Applied Clinical Research, Department of Cancer Research and Molecular Medicine, The Norwegian University of Science and Technology, N-7006 Trondheim, Norway. stian.lydersen@ntnu.no
authors.forename: S
authors.initials: S
authors.lastname: Lydersen
authors.forename: V
authors.initials: V
authors.lastname: Pradhan
authors.forename: P
authors.initials: P
authors.lastname: Senchaudhuri
authors.forename: P
authors.initials: P
authors.lastname: Laake
mesh_terms: D002755:Choice Behavior; D016013:Likelihood Functions; D015233:Models, Statistical; D009664:Norway; D018401:Sample Size; D014184:Transplantation, Homologous / Q000706:statistics & numerical data; D014481:United States