We need a two-way non-parametric ANOVA in order to analysis properly some ecological data, do you know any reference in R? or how to do it? Thank you very much All the best diana -- View this message in context: http://www.nabble.com/Two-way-non-parametric-ANOVA--tp15039308p15039308.html Sent from the R help mailing list archive at Nabble.com.
hits=-2.6 tests=BAYES_00 X-USF-Spam-Flag: NO On Wed, 2008-01-23 at 02:59 -0800, Diana Perdiguero wrote:> We need a two-way non-parametric ANOVA in order to analysis properly some > ecological data, do you know any reference in R? or how to do it? > Thank you very much > All the best > > dianaDiana, If your ecological data are multivariate then take a look at adonis() in package vegan, and the references therein, to see if it is suitable. HTH G -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
Hi Diana, Look at Edgar Brunner's Homepage http://www.ams.med.uni-goettingen.de/en/sta/e.brunner.html and here: http://www.ams.med.uni-goettingen.de/en/sof/index.html Unfortunately, the R script for a 2x2 design with two groups and two timepoints (f1.ld.f1.r) seems to be broken. Uncommenting the branch to the special case "case2x2" in the script should do well, and more than 2 groups or timepoints seem to be working, too. The basic problem with non-parametric (i.e. ordinal) Anova with more than one factor is that the covariance matrix is not homoscedastic anymore after a rank transformation, and autoregressive or compound symmetry covariance structures are destroyed. Best wishes, Matthias Diana Perdiguero schrieb:> We need a two-way non-parametric ANOVA in order to analysis properly some > ecological data, do you know any reference in R? or how to do it? > Thank you very much > All the best > > diana >
Gavin Simpson wrote:> hits=-2.6 tests=BAYES_00 > X-USF-Spam-Flag: NO > > On Wed, 2008-01-23 at 02:59 -0800, Diana Perdiguero wrote: >> We need a two-way non-parametric ANOVA in order to analysis properly some >> ecological data, do you know any reference in R? or how to do it? >> Thank you very much >> All the best >> >> diana > > Diana, > > If your ecological data are multivariate then take a look at adonis() in > package vegan, and the references therein, to see if it is suitable. > > HTH > > G >Also, the proportional odds ordinal logistic model is a generalization of Wilcoxon-Kruskal-Wallis test. It can easily handle interactions in the model. See the lrm function in the Design package or the polr function in the MASS package. For a tutorial on ordinal logistic regression in ecology (using lrm), see @Article{gui00ord, author = {Guisan, Antoine and Harrell, Frank E.}, title = {Ordinal response regression models in ecology}, journal = {Journal of Vegetation Science}, year = 2000, volume = 11, pages = {617-626}, annote = {teaching;ordinal logistic model} } -- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University
> We need a two-way non-parametric ANOVA in order to analysis properly > some ecological data, do you know any reference in R? or how to do > it? Thank you very much All the best diana >A couple more references here are below. I liked the Scheirer reference. /* Scheirer CJ, Ray WS, Hare N (1976) The analysis of ranked data derived from completely randomized factorial designs. Biometrics 32:429-434 Groggel DJ, Skillings JH (1986) Distribution-free tests for main effects in multifactor designs. American Statistician 40:99-102 */
:) I was curious what you would say! Frank was kind enough to send this off list, but it's worth posting to the thread. On Jan 23, 2008, at 10:52 AM, Frank E Harrell Jr wrote:> David Airey wrote: >>> We need a two-way non-parametric ANOVA in order to analysis >>> properly some ecological data, do you know any reference in R? or >>> how to do it? Thank you very much All the best diana >>> >> A couple more references here are below. I liked the Scheirer >> reference. >> /* >> Scheirer CJ, Ray WS, Hare N (1976) The analysis of ranked data >> derived >> from completely randomized factorial designs. Biometrics 32:429-434 >> Groggel DJ, Skillings JH (1986) Distribution-free tests for main >> effects >> in multifactor designs. American Statistician 40:99-102 >> */ > > My guess is that those are a bit out of date, especially the first > one, when compared to the PO model. > Cheers > Frank > >> ______________________________________________ >> R-help at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > > -- > Frank E Harrell Jr Professor and Chair School of Medicine > Department of Biostatistics Vanderbilt > University
While I defer to Frank as far as expertise goes, not having access to his paper, I googled, and I just read that this kind of model is not possible when there are a lack of ties for ranks in the data, and adds an intercept for every rank in the data set. So while interpretation doesn't get more difficult with additional ranks, unlike the multinonimal model, Frank's suggestion would not fly for continuous data that was transformed to ranks, as opposed to data collected as ordered categories, where it would be preferable. On Jan 23, 2008, at 10:52 AM, Frank E Harrell Jr wrote:> David Airey wrote: >>> We need a two-way non-parametric ANOVA in order to analysis >>> properly some ecological data, do you know any reference in R? or >>> how to do it? Thank you very much All the best diana >>> >> A couple more references here are below. I liked the Scheirer >> reference. >> /* >> Scheirer CJ, Ray WS, Hare N (1976) The analysis of ranked data >> derived >> from completely randomized factorial designs. Biometrics 32:429-434 >> Groggel DJ, Skillings JH (1986) Distribution-free tests for main >> effects >> in multifactor designs. American Statistician 40:99-102 >> */ > > My guess is that those are a bit out of date, especially the first > one, when compared to the PO model. > Cheers > Frank > >> ______________________________________________ >> R-help at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > > -- > Frank E Harrell Jr Professor and Chair School of Medicine > Department of Biostatistics Vanderbilt University