Conditional Power: The Good, The Bad (and The Ugly?)

Music City Center 

Conditional power has been used to define futility boundaries, for sample size re-estimation, and for decision making at in interim point in a clinical trial. The general question is "What is the probability the trial will succeed given what we observe today?" Useful answers to this question depend on how well the treatment effect for the rest of the trial can be approximated. Related quantities of predictive probability of success and, from the beginning of the trial, probability of success according to a prior distribution (average power) will be computed and discussed. The gsDesign R package and its Shiny interface will be discussed. We will discuss how to do computations that are easily interpretable and usable for customers of the quantities derived. We will also caution against problematic uses and interpretation of conditional power.

conditional power

interim analysis

group sequential design

adaptive design 

Biopharmaceutical Section