Statistical Power and Bayesian Assurance in Clinical Trial Design

Abstract

In clinical trial design, statistical power is defined as the probability of rejecting the null hypothesis at a pre-specified true clinical treatment effect, which is conditioned on the true but actually unknown effect. In practice, however, this true effect is never a fixed value, but a range from previously held trials which would lead to underpowered or overpowered trials. In order to incorporate the uncertainties of this observed treatment effect, a Bayesian assurance has been proposed as an alternative to the conventional statistical power. This is defined as the unconditional probability of rejecting the null hypothesis. In this chapter, we will review the transition from conventional statistical power to Bayesian assurance and discuss the computations of Bayesian assurance using a Monte-Carlo simulation-based approach.