Note: This article is one of a series about adaptive design that come from a blog written by Dr. Karen Kesler from 2010 to 2011.  That blog is no longer active, but it contained some great information, so we wanted to re-post it here.

Although we are used to thinking of adaptive designs as new, some of them have actually been around for awhile. The PhRMA white paper series (DIJ 2006 40 (4)) includes group sequential designs and adaptive randomizations. Statisticians have been working on these methods for decades. Take adaptive randomizations—the seminal Pocock and Simon paper was written in 1975 (Biometrics 31:103-115), and there are scores of excellent articles in this area, examining various methods and their impact. Group sequential methods have also been studied extensively. If you want a couple of great books for this area, I recommend Jennison and Turnbull’s Group Sequential Methods with Applications to Clinical Trials and Whitehead’s The Design and Analysis of Sequential Clinical Trials. Both are approachable and will get you well down the road of understanding this fascinating area.