Dear Naiara, I believe that the problem is in your specification of start values: If the two independent variables are numeric, then there are four parameters in the model, not two--i.e., two regression coefficients and two thresholds (or intercepts). But why do you find it necessary to specify the start values in any event?
I hope this helps, John -------------------------------- John Fox Department of Sociology McMaster University Hamilton, Ontario Canada L8S 4M4 905-525-9140x23604 http://socserv.mcmaster.ca/jfox -------------------------------- > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Naiara S. Pinto > Sent: Tuesday, January 24, 2006 4:29 PM > To: r-help@stat.math.ethz.ch > Subject: [R] polr (MASS) > > Hello all, > > I am trying to use polr (the ordered logistic model from > MASS) but I am getting the following error message: > > Error in if (all(pr > 0)) -sum(wt * log(pr)) else Inf : > missing value where TRUE/FALSE needed > > My response variable is a factor with 3 levels and I have 2 > independent variables. I am not sure if I guessed the > starting parameters right, which I imagine could be a source > of error. Here's my code: > > > polr(a~b+c, method="logistic", start=c(10, 0.06)) > > Does anyone have any ideas why I am getting this error message? > > Thank you very much, > > Naiara. > > -------------------------------------------- > Naiara S. Pinto > Ecology, Evolution and Behavior > 1 University Station A6700 > Austin, TX, 78712 > > ______________________________________________ > 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 ______________________________________________ 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
