[R-sig-ME] Bglmer convergence warnings (covariance structure)

[D.J. Damen]

Dear all,

I am trying to fit a binomial model with three factors using the bglmer package in R. My model includes a complex 3x2x2 design; factor c.con.tr has three levels, factor c.type.tr two, and factor c.diff.tr has also two levels. When I try to fit a random-intercept only model, the model produces the following warning:

Warning message:
In get("checkConv", lme4Namespace)(attr(opt, "derivs"), opt$par,  :
  Model failed to converge with max|grad| = 2.02439 (tol = 0.001, component 1)

I figured that I did not specify my covariance structure correctly, but I am at a loss as to how I should change it. The structure of my model is as follows:

riobglmer <- bglmer(contrast~c.con.tr*c.type.tr*c.diff.tr+(1|id)+(1|item.new), data=mydata, family=binomial (link='logit'), fixef.prior= normal(cov = diag(9,12)))

To me, (cov = diag(9,12)), seems to be correct.. Am I missing something important? Suggestions and/or remarks are more than welcome.

Thank you very much in advance.

Best regards,

Debby Damen
PhD Student

Department of Communication and Information Science

Tilburg University
Warandelaan 2, room D410
5037 AB Tilburg

T. +31 13 466  8245
M. d.j.damen at uvt.nl<mailto:d.j.damen at uvt.nl>



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