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A Comparison of Procedures for Adaptive Choice of Location Tests in Flexible Two‐Stage Designs
Author(s) -
Friede Tim,
Kieser Meinhard,
Neuhäuser Markus,
Büning Herbert
Publication year - 2003
Publication title -
biometrical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 63
eISSN - 1521-4036
pISSN - 0323-3847
DOI - 10.1002/bimj.200390013
Subject(s) - statistic , test statistic , computerized adaptive testing , computer science , interim , sample size determination , rank (graph theory) , adaptive design , interim analysis , statistical hypothesis testing , statistics , sample (material) , data mining , mathematical optimization , mathematics , clinical trial , medicine , chemistry , archaeology , pathology , combinatorics , chromatography , history , psychometrics
Although linear rank statistics for the two‐sample problem are distribution free tests, their power depends on the distribution of the data. In the planning phase of an experiment, researchers are often uncertain about the shape of this distribution and so the choice of test statistic for the analysis and the determination of the required sample size are based on vague information. Adaptive designs with interim analysis can potentially overcome both problems. And in particular, adaptive tests based on a selector statistic are a solution to the first. We investigate whether adaptive tests can be usefully implemented in flexible two‐stage designs to gain power. In a simulation study, we compare several methods for choosing a test statistic for the second stage of an adaptive design based on interim data with the procedure that applies adaptive tests in both stages. We find that the latter is a sensible approach that leads to the best results in most situations considered here. The different methods are illustrated using a clinical trial example.