Abstract
This paper describes a Bayesian approach to the design and analysis of clinical trials, with special reference to Phase III drug trials. The focus is on two rather general areas that are important in clinical trials: (1) monitoring trials with the possibility of changing the trial's design, and (2) combining various sources of information concerning the effect of the drug. Topics covered include survival analysis, analysis of trials in which the patients have different prognoses, multicenter trials and meta-analysis.