[R-sig-ME] how to set the starting value in lme

Ben Bolker bbolker at gmail.com
Fri Mar 18 17:36:10 CET 2011

On 11-03-18 12:41 AM, jia liu wrote:
> Hi, When I fit the mixed-effects model by lme, I got the convergence
> error code = 1,message = iteration limit reached without
> convergence (9). Even after I increase the iteration numbers, it
> still did not work. The only way I found to avoid the error message
> is to increase the number of iterations for the EM algorithm, which
> need to be at least 1100. But the weird thing is that the correlation
> between two random coefficients is always around 1, which is not
> true. I also tried to fit the model by lmer and it also gave me the
> correlation as 1. So I am thinking the error should be related with
> the improper starting value. But I do not know how to set up my
> desired starting value in lme function. Are there anybody know it? Or
> met the same problem with me before and know how to avoid the error?
> Thank you for your help. Bests, Jia
  I think you've asked this question before, and I've answered it.
(1) I don't think your problem is poor starting conditions, but an
overfitted model.  I don't think changing the starting conditions is
going to help.
(2) To the best of my knowledge it is not possible to change the
starting conditions in lme, without significant hacking.
(3) You can change the starting conditions in lmer: see the manual page
(?lmer) and search for "start" ...

  Ben Bolker

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