R help - May 2006 - Problem in using confint method on polr model object

I fit a proportional odds model
with the polr-function of the MASS package from
Venables and Ripley 
 

Applying the confint method to  calculate confidence intervals for the
parameters I get 
the following error message
 

Waiting for profiling to be done...
Re-fitting to get Hessian
Error in X[, -i, drop = FALSE] : incorrect number of dimensions
 
Can someone explain the error-message?
 
(The data are from McCullagh (1980), JRSS,B)
 
 

tonsiles<-data.frame(carrier=factor(rep(c('yes','no'),each=3)),
                     size=ordered(rep(c(1,2,3),2)),
                     count=c(19,29,24,497,560,269))
library(MASS)
m<-polr(size~carrier,data=tonsiles,weights=count)
 confint(m)
 

Ulrich
 

platform       i386-pc-mingw32           
arch           i386                      
os             mingw32                   
system         i386, mingw32             
status                                   
major          2                         
minor          3.0                       
year           2006                      
month          04                        
day            24                        
svn rev        37909                     
language       R                         
version.string Version 2.3.0 (2006-04-24)
 

Ulrich Halekoh
Danish Institute of Agricultural Sciences
Unit of Statistics and Decision Analysis
Denmark
 

	[[alternative HTML version deleted]]

On Wed, 3 May 2006, Ulrich Halekoh wrote:
> I fit a proportional odds model
> with the polr-function of the MASS package from
> Venables and Ripley
>
>
> Applying the confint method to  calculate confidence intervals for the
> parameters I get
> the following error message
>
>
> Waiting for profiling to be done...
> Re-fitting to get Hessian
> Error in X[, -i, drop = FALSE] : incorrect number of dimensions
>
> Can someone explain the error-message?
This is a single-coefficient model, and in profile.polr
it needs to be

     X <- model.matrix(fitted)[, -1, drop = FALSE]


>
> (The data are from McCullagh (1980), JRSS,B)
>
>
>
>
tonsiles<-data.frame(carrier=factor(rep(c('yes','no'),each=3)),
>                     size=ordered(rep(c(1,2,3),2)),
>                     count=c(19,29,24,497,560,269))
> library(MASS)
> m<-polr(size~carrier,data=tonsiles,weights=count)
> confint(m)
>
>
> Ulrich
>
>
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          3.0
> year           2006
> month          04
> day            24
> svn rev        37909
> language       R
> version.string Version 2.3.0 (2006-04-24)
>
>
> Ulrich Halekoh
> Danish Institute of Agricultural Sciences
> Unit of Statistics and Decision Analysis
> Denmark
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595