Ramon Martínez Coscollà wrote: > Hi all!! > > I am using a proportinal odds model to study some ordered categorical > data. I am trying to predict one ordered categorical variable taking > into account only another categorical variable. > > I am using polr from the R MASS library. It seems to work ok, but I'm > still getting familiar and I don't know how to assess goodness of fit. > I have this output, when using response ~ independent variable: > > Residual Deviance: 327.0956 > AIC: 333.0956 >> polr.out$df.residual > [1] 278 >> polr.out$edf > [1] 3 > > When taking out every variable... (i.e., making formula: response ~ 1), I > have: > > Residual Deviance: 368.2387 > AIC: 372.2387 > > How can I test if the model fits well? How can I check that the > independent variable effectively explains the model? Is there any > test? > > Moreover, sendig summary(polr.out) I get this error: > > > Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess, ...) : > initial value in 'vmmin' is not finite > > Something to do with the optimitation procedure... but, how can I fix > it? Any help would be greatly appreciated. > > Thanks.
You might also look at lrm and residuals.lrm in the Design package, which provides partial and score residual plots to check PO model assumptions. -- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University ______________________________________________ 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.