Name: John Lawrence

Firstname: John

Title: Dr.

Institution: Food & Drug Administration

Street: 12119 amber ridge circle

City: Germantown

Zip-Code: 20876

Country: USA

Phone: 301 594-5375

Fax: 301 594-5494


Authors: John Lawrence

Title: Changing the test statistic after an interim analysis

Abstract: Often, there are a wide variety of test statistics that can be used to test a specific set of hypotheses. For example, there are many different statistics that can be used to test for equality of the distributions of a time-to-event endpoint, e.g. the logrank or the Gehan-Wilcoxon statistic. After an interim look at the data, the investigator may decide that a different test statistic would be more powerful. But, changing the test statistic can inflate the type I error rate. In this talk, I will discuss a strategy for changing the test statistic that maintains the correct type I error rate. A simulation study demonstrates that this strategy can result in a procedure that has higher power than the test without adaptation.