Adaptive Sample Size Calculations in Group Sequential Trials
Article first published online: 25 MAY 2004
Volume 55, Issue 4, pages 1286–1290, December 1999
How to Cite
Lehmacher, W. and Wassmer, G. (1999), Adaptive Sample Size Calculations in Group Sequential Trials. Biometrics, 55: 1286–1290. doi: 10.1111/j.0006-341X.1999.01286.x
- Issue published online: 25 MAY 2004
- Article first published online: 25 MAY 2004
- Received June 1998. Revised August and November 1998 and February 1999. Accepted February 1999.
- Adaptive interim analysis;
- Clinical trials;
- Group sequential tests;
- Sample size
Summary. A method for group sequential trials that is based on the inverse normal method for combining the results of the separate stages is proposed. Without exaggerating the Type I error rate, this method enables data-driven sample size reassessments during the course of the study. It uses the stopping boundaries of the classical group sequential tests. Furthermore, exact test procedures may be derived for a wide range of applications. The procedure is compared with the classical designs in terms of power and expected sample size.