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Outline

Rank test statistics for unbalanced nested designs

2008, Statistical Methodology

https://doi.org/10.1016/J.STAMET.2007.06.001

Abstract

We formulate rank statistics for testing hypotheses in unbalanced, and possibly heteroscedastic, twofactor nested designs with independent observations. These include Wald-type statistics based on the theory introduced by Akritas, Arnold and Brunner, as well as a Box-type approximation which is intended to improve the accuracy of approximation to asymptotic distributions. We also present statistics based on a recent theory of weighted F-statistics for ranks. The actual sizes of the statistics at various nominal levels are compared in a simulation study. Our main conclusion is that the Box-adjusted Wald-type statistic is the only statistic that is accurate across all the situations considered and therefore we recommend it for general use.

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