[R-sig-ME] singular convergence with lmer()

Joshua Wiley jwiley.psych at gmail.com
Sun Jul 8 22:52:18 CEST 2012

Notice that the variance of one of your random effects is estimated at
0.  I suspect that this is the source of the singular convergence.
IIRC proc mixed (which is what I assume you are using in SAS) uses a
somewhat different approach to to estimate the random effects than
does lme4.

Although it seems to work for Reinhold, again some of the variances
are vanishingly small, which seems to me like it may suggest some of
the effects are borderline on 0 and perhaps slightly different
estimation methods either get "really small" or simply "0" and if 0,
you get a warning.  I would also consider simplifying your model
(although likelihood ratio tests seem to suggest a significant
decrement in the likelihood fixing the variance at 0).



On Thu, Jul 5, 2012 at 1:01 AM, laurent stephane <laurent_step at yahoo.fr> wrote:
> Dear all,
> Using the latest CRAN version of lme4 I get the following warning from lmer() :
> Warning message:
> In mer_finalize(ans) : singular convergence (7)
> My model is not complicated and it works fine with SAS (if you are interested in the details of my model see forums.cirad.fr/logiciel-R/viewtopic.php?t=5071 )
> What argument could I change in lmer() to overcome this warning ?
> Kind regards,
> SL
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Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles

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