[R] Re:[ R] Wilcoxon test for mixed deisgn

Cliff Lunneborg cliff at ms.washington.edu
Mon Jan 24 22:23:24 CET 2005


Marco Chirandini writes:

"is there any extension of the pairwise Wilcoxon test to a dependent
samples layout with replicates (or, in other terms, a one-way layout
with blocking and replicates)?

The Wilcoxon method with matched pairs works for the case of dependent
samples with one observation per block, while the Mann-Whitney test
works for independent samples, thus one single block and replicated
observations. Is there a method which mixes this two cases considering a
depedent sample design in which each block has more than one
observation? I know it exists a Friedman test for this case but in the
Friedman test ranks are constructed considering all subjects jointly,
while in Wilcoxon only the pair of subject currently considered are
ranked, thus resulting in a more powerful test."

It is my understanding that the Friedman test ranks responses within
each block, independently from block to block.

friedman.test() is an R function.

**********************************************************
Cliff Lunneborg, Professor Emeritus, Statistics &
Psychology, University of Washington, Seattle
cliff at ms.washington.edu




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