[R] Two factor (or more) non-parametric comparison of means

[Peter Dalgaard]

"Marc Schwartz (via MN)" <mschwartz at mn.rr.com> writes:

> I suspect that John may be looking for ?friedman.test, which I believe
> will allow for a two-way non-parametric test.

You could be right, but you could also be wrong... It depends quite a
bit on what is meant by a "two-factor  comparison of means". If he
literally means means (!), then a permutation test (permuting within
levels of the other factor) could be appropriate. It also makes a
difference whether there's a single replication or more per cell in
the cross-classification.

> kruskal.test() will perform a non-parametric test on two or more samples
> (or factor levels) as a generalization of wilcox.test() for one or two
> samples (or factor levels).
> 
> HTH,
> 
> Marc Schwartz
> 
> On Tue, 2005-10-11 at 18:22 +0200, Johan Sandblom wrote:
> > ?kruskal.test
> > 
> > 2005/10/11, John Sorkin <jsorkin at grecc.umaryland.edu>:
> > > Can anyone suggest a good non-parametric test, and an R
> > implementation of the test,  that allows for two or more factors?
> > Wilcoxon signed rank allows for only one.
> > > Thanks,
> > > John
> 
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