Related Experiment Video
Updated: Aug 12, 2026

Barnes Maze Testing Strategies with Small and Large Rodent Models
Published on: February 27, 2014
A group sequential test for survival trials: an alternative to rank-based procedures
Z Li1
1Department of Biometrics and Statistical Sciences, The Procter and Gamble Company, Cincinnati, OH 45242, USA. li.z@pg.com
Abstract:
A method of interim monitoring is described for survival trials in which the proportional hazards assumption may not hold. This method extends the test statistics based on the cumulative weighted difference in the Kaplan-Meier estimates (Pepe and Fleming, 1989, Biometrics 45, 497-507) to the sequential setting. Therefore, it provides a useful alternative to the group sequential linear rank tests. With an appropriate weight function, the test statistic itself provides an estimator for the cumulative weighted difference in survival probabilities, which is an interpretable measure for the treatment difference, especially when the proportional hazards model fails. The method is illustrated based on the design of a real trial. The operating characteristics are studied through a small simulation.
Related Concept Videos
Introduction To Survival Analysis
The primary goal of survival analysis is to estimate survival time—the time until a...
Survival Curves
The Kaplan-Meier estimator is the most common method for constructing survival curves. This...
Assumptions of Survival Analysis
Comparing the Survival Analysis of Two or More Groups
The Mantel-Cox Log-Rank Test
Survival Tree
Building a Survival Tree
Constructing a survival tree begins...

