[R] "False convergence" in LME

[Spencer Graves]

      This is a common problem, for which solutions are poorly documented. 

           1.  Have you tried fitting simpler models, in the hopes of 
getting something that converges without complaint, then use 'update' to 
try more complicated models?  It sometimes works, though often not. 

           2.  Also, have you tried something like 'lme(..., 
control=lmeControl(returnObject=TRUE))'?  If no, I suggest you try this 
first.  With the error message you report, I would expect this to work, 
though it may not. 

           3.  Finally, have you tried something like 'lme(..., 
control=lmeControl(singular.ok=TRUE))' OR 'lme(..., 
control=lmeControl(singular.ok=TRUE, returnObject=TRUE))'?  I'm not 
sure, but I believe this may work when "returnObject=TRUE" does not. 

           4.  Have you tried the following: 

                library(FinTS)
                package.dir('nlme')

                I tried this just now and learned that the 'nlme' 
packages contains two non-standard subdirectories named "mlbook" and 
"scripts".  The second contains files names 'ch01.R', 'ch02.R', etc., 
which contain the R commands required to reproduce virtually all the 
figures, tables and examples in Pinheiro and Bates (2000) Mixed-Effects 
Models in S and S-PLUS (Springer).  If you have not already done so, I 
recommend you get this book and use these script files to facilitate 
your study of it.  Doug Bates is one of the world's leading experts in 
mixed-effects modeling, and I have learned a lot from my study of it. 

      Hope this helps. 
      Spencer Graves    

Rebecca Sela wrote:
> I tried to use LME (on a fairly large dataset, so I am not including it), and I got this error message:
>
> Error in lme.formula(formula(paste(c(toString(TargetName), "as.factor(nodeInd)"),  : 
>   nlminb problem, convergence error code = 1
>   message = false convergence (8)
>
> Is there any way to get more information or to get the potentially wrong estimates from LME?
>
> (Also, the page in the NLMINB documentation,  http://netlib.bell-labs.com/cm/cs/cstr/153.pdf, has errors in it, which makes it harder to check on what is happening.)
>
> Thank you in advance!
>
> Rebecca
>
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