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Editors-in-chief: Bettina Grün, Torsten Hothorn, Edzer Pebesma, Achim Zeileis    ISSN 1548-7660; CODEN JSSOBK
Mann-Whitney Type Tests for Microarray Experiments: The R Package gMWT | Fischer | Journal of Statistical Software
Authors: Daniel Fischer, Hannu Oja
Title: Mann-Whitney Type Tests for Microarray Experiments: The R Package gMWT
Abstract: We present the R package gMWT which is designed for the comparison of several treatments (or groups) for a large number of variables. The comparisons are made using certain probabilistic indices (PI). The PIs computed here tell how often pairs or triples of observations coming from different groups appear in a specific order of magnitude. Classical two and several sample rank test statistics such as the Mann-Whitney-Wilcoxon, Kruskal-Wallis, or Jonckheere-Terpstra test statistics are simple functions of these PI. Also new test statistics for directional alternatives are provided. The package gMWT can be used to calculate the variable-wise PI estimates, to illustrate their multivariate distribution and mutual dependence with joint scatterplot matrices, and to construct several classical and new rank tests based on the PIs. The aim of the paper is first to briefly explain the theory that is necessary to understand the behavior of the estimated PIs and the rank tests based on them. Second, the use of the package is described and illustrated with simulated and real data examples. It is stressed that the package provides a new flexible toolbox to analyze large gene or microRNA expression data sets, collected on microarrays or by other high-throughput technologies. The testing procedures can be used in an eQTL analysis, for example, as implemented in the package GeneticTools.

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Paper: Mann-Whitney Type Tests for Microarray Experiments: The R Package gMWT     Download PDF (Downloads: 2281)
gMWT_1.0.tar.gz: R source package Download (Downloads: 124; 39KB)
v65i09.R: R example code from the paper Download (Downloads: 117; 6KB) Data sets for replication materials Download (Downloads: 96; 335KB)

DOI: 10.18637/jss.v065.i09

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Code: GNU General Public License (at least one of version 2 or version 3) or a GPL-compatible license.