convergence in polr

Why have you sent a message about S-PLUS to R-help, one that has already 
been answered on S-news?

There is no function nlminb in R.

Hello splus-users, I am trying to fit a regression model for an ordered 
response factor. So I am using the function polr in library(MASS). My data 
is a matrix of 1665 rows and 63 columns (one of the column is the dependent 
variable). The code I use is polr(as.ordered(q23p)~.,data=newdatap)
 but I am getting the following warning message singularity encountered in: 
nlminb.1(temp, p, liv, lv, objective, gradient, bounds, scale)

I looked in the MASS help for nlminb and I found that for the function
nlminb(start, objective, gradient=NULL, hessian=NULL,  
       scale=1, control=NULL, lower=-Inf, upper=Inf) 

when returning a warning message of singularity means that the optimization 
algorithm thinks it can't make any further progress because it has too many 
degrees of freedom. It usually means that the objective function is either 
not differentiable, or it may not have an optimum.

So for my data an optimum can't be obtained.
Is this true?

Can I ignore this warning message since what I want to find is values for 
the boundaries? Will the values for the boundaries be accurate even though 
I get the warning message?

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://www.stat.math.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

convergence in polr

Thread (2 messages)