ABSTRACT
This chapter describes an example concerning clinical trials with extremely low incidence rate to illustrate the issue of infeasible sample size requirement as a result of power calculation. It outlines classical methods for sample size determination and explains the application of a Bayesian approach with a noninformative uniform prior. The chapter describes prestudy power analysis and precision analysis for sample size calculation. It also outlines an alternative method for sample size determination for clinical studies with extremely low incidence rate and a statistical procedure for data safety monitoring based on probability statement during the conduct of a clinical trial with extremely low incidence rate proposed by Chow and Chiu. The idea of Chow and Chiu's procedure is to justify a selected sample size based on a precision analysis and a sensitivity analysis in conjunction with a power analysis. Chow and Chiu's proposed method reduces the sample size required for achieving a desired precision with certain statistical assurance.
