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Two factor (or more) non-parametric comparison of means
5 messages · John Sorkin, Johan Sandblom, Peter Dalgaard +1 more
?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
John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC and
University of Maryland School of Medicine Claude Pepper OAIC
University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
410-605-7119
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-- Johan Sandblom N8, MRC, Karolinska sjh t +46851776108 17176 Stockholm m +46735521477 Sweden "What is wanted is not the will to believe, but the will to find out, which is the exact opposite" - Bertrand Russell
I suspect that John may be looking for ?friedman.test, which I believe will allow for a two-way non-parametric test. 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
"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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O__ ---- Peter Dalgaard ??ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
Peter, Good points all around. Hopefully John will provide further clarification. Best regards, Marc
On Tue, 2005-10-11 at 19:46 +0200, Peter Dalgaard wrote:
"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
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html