title: Unbiased estimation of selected treatment means in two-stage trials.
abstract: Straightforward estimation of a treatment's effect in an adaptive clinical trial can be severely hindered when it has been chosen from a larger group of potential candidates. This is because selection mechanisms that condition on the rank order of treatment statistics introduce bias. Nevertheless, designs of this sort are seen as a practical and efficient way to fast track the most promising compounds in drug development. In this paper we extend the method of Cohen and Sackrowitz (1989) who proposed a two-stage unbiased estimate for the best performing treatment at interim. This enables their estimate to work for unequal stage one and two sample sizes, and also when the quantity of interest is the best, second best, or j -th best treatment out of k. The implications of this new flexibility are explored via simulation.
authors.affiliation: MRC Biostatistics Unit, Cambridge, CB2 0SR, UK. jack.bowden@mrc-bsu.cam.ac.uk
authors.forename: Jack
authors.initials: J
authors.lastname: Bowden
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Glimm
mesh_terms: D000465:Algorithms; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003198:Computer Simulation; D006801:Humans; D015233:Models, Statistical; D015203:Reproducibility of Results; D016896:Treatment Outcome