Sample-Size Reestimation Design
Mark Chang · 2015
Despite a great effort, we often face a high degree of uncertainty about param- eters when designing a trial or justifying the sample-size at the design stage. This could involve the initial estimates of treatment effect and variability. When the uncertainty is greater, a classical design with a fixed sample-size is inappropriate. Instead, it is desirable to have a trial design that allows for reestimation of sample-size at the interim analysis. Several different methods have been proposed for sample-size reestimation (SSR), including the blinded, unblinded, and mixed methods.