At 08:51 02/08/2007, Ramon Martínez Coscollà wrote: >Hi all!! There is no need to post twice, nor to also post on allstat.
Pages 204-205 of MASS for which this software is a support tool provides ample information on how to compare models. >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. Michael Dewey http://www.aghmed.fsnet.co.uk ______________________________________________ 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.