Media type: E-Article Title: Choice of alpha spending function and time points in clinical trials with one or two interim analyses Contributor: Selwyn, Murray R.; Fish, Susan M. imprint: Wiley, 2004 Published in: Pharmaceutical Statistics, 3 (2004) 3, Seite 193-203 Language: English DOI: 10.1002/pst.108 ISSN: 1539-1604; 1539-1612 Keywords: Pharmacology (medical) ; Pharmacology ; Statistics and Probability Origination: Footnote: Description: <jats:title>Abstract</jats:title><jats:p>One characterization of group sequential methods uses alpha spending functions to allocate the false positive rate throughout a study. We consider and evaluate several such spending functions as well as the time points of the interim analyses at which they apply. In addition, we evaluate the double triangular test as an alternative procedure that allows for early termination of the trial not only due to efficacy differences between treatments, but also due to lack of such differences. We motivate and illustrate our work by reference to the analysis of survival data from a proposed oncology study.</jats:p><jats:p>Such group sequential procedures with one or two interim analyses are only slightly less powerful than fixed sample trials, but provide for the strong possibility of early stopping. Therefore, in all situations where they can practically be applied, we recommend their routine use in clinical trials. The double triangular test provides a suitable alternative to the group sequential procedures in that they do not provide for early stopping with acceptance of the null hypothesis. Again, there is only a modest loss in power relative to fixed sample tests. Copyright © 2004 John Wiley & Sons, Ltd.</jats:p>