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 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
