title: Sample-size calculations for studies with correlated ordinal outcomes.
abstract: Correlated ordinal response data often arise in public health studies. Sample-size (power) calculations are a crucial step in designing such studies to ensure an adequate sample to detect a significant effect. Here we extend Rochon's method of sample-size estimation with a repeated binary response to the ordinal case. The proposed sample-size calculations are based on an analysis with generalized estimating equations (GEE) and inference with the Wald test. Simulation results demonstrate the merit of the proposed power calculations. Analysis of an arthritis clinical trial is used for illustration.
authors.affiliation: Division of HIV/AIDS Prevention (MS E-37), National Centers for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., NE, Atlanta, GA 30333, USA. kimhy@email.unc.edu
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: John M
authors.initials: JM
authors.lastname: Williamson
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Lyles
mesh_terms: D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D001310:Auranofin / Q000627:therapeutic use; D003198:Computer Simulation; D006801:Humans; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D012107:Research Design; D018401:Sample Size
chemical_list: D018501:Antirheumatic Agents; D001310:Auranofin