Calculating predicted probabilities for ordinal logistic regression

Question

I've run an ordered logistic regression model in R with Zelig and am looking to calculate predicted probabilities. Zelig has a series of simple one line commands to generate the information I want on first differences and so forth. Unfortunately, I keep getting an error when running the zelig function and was wondering if there was a quick alternative for generating predicted probabilities for a ordered logit in R.

For what it's worth, here's the error from my Zelig code.

> x.out <- setx(mod, credit=1)
Error in dta[complete.cases(mf), names(dta) %in% vars, drop = FALSE] : 
  incorrect number of dimensions

I just need an alternative solution that I can use to generate the probabilities.

Answer 1

A similar issue was raised on Stack Overflow more than one year ago. I don't know if re-installing Zelig and its dependencies will solve your problem (especially because I would prefer to understand why this error message came up before reinstalling).

Anyway, you can use the lrm() function from the rms package, as it allows to fit several models for categorical outcomes including proportional odds model. There is a predict() (but also Predict()) function to get the desired predicted values. As an alternative, you may want to look at the ordinal package (see the clm() function).