title: On group sequential designs comparing two binomial proportions.
abstract: Discussed is the problem of sample size determination for one- and two-stage hypothesis tests comparing two binomial proportions using two independent random samples. A FORTRAN compiled search algorithm identifies exact group sequential designs that allow early stopping only for futility or only for efficacy or for either futility or efficacy. The resulting designs yield a substantial savings in terms of total sample size in many practical cases, are seen to satisfy a number of desirable properties, and are compared to other exact one- and two-stage designs and to designs derived based upon asymptotic normal theory methods.
authors.affiliation: Statistics and Evaluation Center, American Cancer Society, Atlanta, Georgia 30303-1002, USA. james.kepner@cancer.org
authors.forename: James L
authors.initials: JL
authors.lastname: Kepner
mesh_terms: D017322:Clinical Trials, Phase II as Topic / Q000706:statistics & numerical data*; D017326:Clinical Trials, Phase III as Topic / Q000706:statistics & numerical data*; D006801:Humans; D015233:Models, Statistical; D012107:Research Design / Q000706:statistics & numerical data; D018401:Sample Size