title: Bayesian sample size for exploratory clinical trials incorporating historical data.
abstract: This paper presents a simple Bayesian approach to sample size determination in clinical trials. It is required that the trial should be large enough to ensure that the data collected will provide convincing evidence either that an experimental treatment is better than a control or that it fails to improve upon control by some clinically relevant difference. The method resembles standard frequentist formulations of the problem, and indeed in certain circumstances involving 'non-informative' prior information it leads to identical answers. In particular, unlike many Bayesian approaches to sample size determination, use is made of an alternative hypothesis that an experimental treatment is better than a control treatment by some specified magnitude. The approach is introduced in the context of testing whether a single stream of binary observations are consistent with a given success rate p(0). Next the case of comparing two independent streams of normally distributed responses is considered, first under the assumption that their common variance is known and then for unknown variance. Finally, the more general situation in which a large sample is to be collected and analysed according to the asymptotic properties of the score statistic is explored.
authors: Medical and Pharmaceutical Statistics Research Unit, Department of Mathematics and Statistics, Lancaster University, Lancaster, UK. j.whitehead@lancaster.ac.uk
authors: John
authors: J
authors: Whitehead
authors: Elsa
authors: E
authors: Valdés-Márquez
authors: Patrick
authors: P
authors: Johnson
authors: Gordon
authors: G
authors: Graham
mesh_terms: D001499:Bayes Theorem; D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use; D018401:Sample Size; D014552:Urinary Tract Infections / Q000188:drug therapy
chemical_list: D010726:Phosphodiesterase Inhibitors