Dear R users, Does anyone know if it is possible to use multinom to do a polychotomous fit using one categorical and one numeric variable as response. The doc. for multinom states that for formula , response can be K>2 classes. Is this 2 and more, or as I have understood it only greater than 2. I have tried fitting my data, but have only encountered error messages. On another note, Is it possible to get a set of discriminant scores for the multinom fit using predict.nnet or some other function like for lda using predict.lda? Thanks Peter ------------- Peter Ho Universidade Cat?lica Portuguesa Escola Superior de Biotecnologia Rua Dr. Ant?nio Bernardino de Almeida 4200-072 Porto -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Peter Ho asks:> Dear R users, > > Does anyone know if it is possible to use multinom to do a polychotomous > fit using one categorical and one numeric variable as response. The > doc. for multinom states that for formula, response can be K>2 classes. > Is this 2 and more, or as I have understood it only greater than 2. I > have tried fitting my data, but have only encountered error messages.If you have a bivariate response, on variable categorical and one continuous (if that't what you mean by "numeric"), then the response is not "polychotomous" and multinom is of no use to you. For multinom to be useful, you need to express your response categories through a single factor variable. If it is naturally expressed with more than two factors, you have to combine them into one factor in the way you intend the result to be interpreted. It should work with K = 2 categories and the result should be comparable with glm(..., family = binom, ...) and contr.treatment contrasts.> On another note, Is it possible to get a set of discriminant scores for > the multinom fit using predict.nnet or some other function like for lda > using predict.lda?There is a predict.multinom method in the nnet library that allows some forms of prediction following on from a multinom fit. -- Bill Venables, Statistician, CMIS Environmetrics Project CSIRO Marine Labs, PO Box 120, Cleveland, Qld, AUSTRALIA. 4163 Tel: +61 7 3826 7251 Email: Bill.Venables at cmis.csiro.au Fax: +61 7 3826 7304 http://www.cmis.csiro.au/bill.venables/ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On Mon, 20 Mar 2000, Peter Ho wrote:> Dear R users, > > Does anyone know if it is possible to use multinom to do a polychotomous > fit using one categorical and one numeric variable as response. The > doc. for multinom states that for formula , response can be K>2 classes. > Is this 2 and more, or as I have understood it only greater than 2. I > have tried fitting my data, but have only encountered error messages.It does work for K=2, but is not recommended. But what you want is not a polychotomous fit, as that has only categories.> On another note, Is it possible to get a set of discriminant scores for > the multinom fit using predict.nnet or some other function like for lda > using predict.lda?Um, what do such scores mean? You can hack predict.multinom to do this, but only differences in scores are relevant. It fits probabilities, only. -- Brian D. Ripley, ripley at stats.ox.ac.uk 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 mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Prof Brian D Ripley wrote:> > On another note, Is it possible to get a set of discriminant scores for > > the multinom fit using predict.nnet or some other function like for lda > > using predict.lda? > > Um, what do such scores mean? You can hack predict.multinom to do this, > but only differences in scores are relevant. It fits probabilities, only.What I wanted here was for some way to have a graphical view of a logistic discrimination, like lda does with plotting discriminant scores. Most non statisticians find graphical display of results easier to understand. Many Journals prefer graphics instead of tables to show results. Apologies for my ignorance. I have never used Logistic discrimination before and I am still trying to understand some of the concepts. Thanks Peter ----------------------------------- Peter Ho Escola Superior de Biotecnologia Universidade Cat?lica Portuguesa Rua Dr. Ant?nio Bernardino de Almeida 4200-072 Porto Portugal -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._