On Fri, 2 Feb 2007, Henric Nilsson (Public) wrote: > Den Fr, 2007-02-02, 06:03 skrev Stacey Buckelew: >> Hi, >> >> I am working on a regression tree in Rpart that uses a continuous response >> variable that is ordered. I read a previous response by Pfr. Ripley to a >> inquiry regarding the ability of rpart to handle ordinal responses in >> 2003. At that time rpart was unable to implement an algorithm to handle >> ordinal responses. Has there been any effort to rectify this in recent >> years? > > The `ctree' function in the `party' package is able to handle ordered > responses, but note that there are fundamental differences between the > former and `rpart'. Reading the package vignette and the relevant > references will help. >
Hi Henric, > However, at the moment there seems to be a problem related to the ordinal > case (predicted probabilities > 1) and I've CC:ed the package's maintainer > (Torsten Hothorn). > yep, you are right (as always)-- a bug introduced by a fix, grrr. Its a little bit more complicated, but I'll make correct predictions available again *asap*. Thanks! Torsten > > HTH, > Henric > > - - - - - > > Torsten, consider the following: > >> ### ordinal regression >> mammoct <- ctree(ME ~ ., data = mammoexp) > Warning message: > no admissible split found >> ### estimated class probabilities >> treeresponse(mammoct, newdata = mammoexp[1:5, ]) > [[1]] > [1] 1.822115 > > [[2]] > [1] 1.265487 > > [[3]] > [1] 1.822115 > > [[4]] > [1] 1.560440 > > [[5]] > [1] 1.822115 > >> sessionInfo() > R version 2.4.1 Patched (2007-01-06 r40399) > i386-pc-mingw32 > > locale: > LC_COLLATE=Swedish_Sweden.1252;LC_CTYPE=Swedish_Sweden.1252;LC_MONETARY=Swedish_Sweden.1252;LC_NUMERIC=C;LC_TIME=Swedish_Sweden.1252 > > attached base packages: > [1] "stats4" "grid" "splines" "stats" "graphics" "grDevices" > [7] "utils" "datasets" "methods" "base" > > other attached packages: > party vcd colorspace MASS strucchange sandwich > "0.9-8" "1.0-2" "0.95" "7.2-31" "1.3-1" "2.0-1" > zoo coin mvtnorm modeltools survival > "1.2-2" "0.5-2" "0.7-5" "0.2-10" "2.30" >> > > > > > > >> >> Thanks! >> >> Stacey >> >> >> >> On Mon, 2 Jun 2003, Andreas Christmann wrote: >>>>>> 1. RE: Ordinal data - Regression Trees & Proportional Odds >>> (Liaw, Andy) >>> >>>> AFAIK there's no implementation (or description) of tree algorithm >>>> that handles ordinal response. >>>> >>> >>> Regression trees with an ordinal response variable can be computed with >>> SPSS Answer Tree 3.0. >> They *can* be handled by tree or rpart in R. >> I think Andy's point was that there is no consensus as to the right way to >> handle them: certainly using the codes of categories works and may often >> be reasonable, and treating ordinal responses as categorical is also very >> often perfectly adequate. >> Note that rpart is user-extensible, so it would be reasonably easy to >> write >> an extension for a proportional-odds logistic regression model, if that is >> thought appropriate (and it seems strange to me to impose such strong >> structure on the model with such a general `linear predictor': POLR >> models are often in my experience a poor reflection of real problems). >> -- >> Brian D. Ripley, [EMAIL PROTECTED] >> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ >> University of Oxford, Tel: +44 1865 272861 (self) >> 1 South Parks Road, +44 1865 272860 (secr) >> Oxford OX1 3TG, UK Fax: +44 1865 272595 >> >> ______________________________________________ >> R-help@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 >> and provide commented, minimal, self-contained, reproducible code. >> >> > > ______________________________________________ R-help@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 and provide commented, minimal, self-contained, reproducible code.