Re: [R] polr (MASS)

From: John Fox <jfox_at_mcmaster.ca>
Date: Wed 25 Jan 2006 - 12:27:18 EST


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: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] 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
>
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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 Received on Wed Jan 25 12:37:34 2006

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