A comparison of the constant piecewise weighted logrank and Fleming-Harrington tests

The Fleming-Harrington and constant piecewise wei- ghted logrank tests for late effects in clinical trials are considered. Both tests depend on a parameter (q for the Fleming-Harrington and t* for the constant piecewise weighted logrank) that has to be chosen before the trial analysis. The problem of choosing the most appropriate test and associated parameter value for a given trial is addressed. For this purpose, the tests are compared in terms of their sensitivity to q and t* and of their asymptotic relative efficiency and necessary sample size. Some guidelines for choosing the most appropriate weight for testing late effects are provided. The methodology is illustrated on a medical dataset.