[R-sig-ME] Convergence issues running clmm in ordinal package

[David Duffy]

On Wed, 20 Apr 2011, Karen Lamb wrote:

> Hi all,
>
> I have a data set containing around 8148 individuals nested within 
> approximately 2548 areas (DZID). I have an ordinal response (Num20) with 
> 5 categories (0=None, 1=1 to 3, 2=4 to 11, 3=12 to 19, 4=20 and over) 
> and have been trying to fit multilevel models using the clmm() function 
> in the ordinal package to examine the statistical significance of 
> individual (e.g. Sex, Car, Age, Limitill, Nssec3) and area level 
> predictors (e.g. TotalPA) that I have.

>
>> mod.a <- clmm(Num20~1, random=DZID, na.action=na.omit)
> Warning message:
> clmm may not have converged:
>  optimizer 'ucminf' terminated with max|gradient|: 0.000501749472956048

You might try reducing Num20 to fewer categories (including 2) and see if 
fitting is then successful.  Also try other programs eg MCMCglmm (R 
package), MIXORE, WinBUGS, and see if the answers are concordant, even if 
clmm fails to converge.

Cheers, David Duffy.