[R-sig-ME] algorithm did not converge when running general linear mixed mode (logistic)

[Douglas Bates]

On Thu, Nov 6, 2008 at 10:19 AM, Miao-Hsuan Yen <melissayen at gmail.com> wrote:
> Dear mixed-list
>
> I am quite new with the lmer program.
> I have a data set with binary response (1, 0 and NA for missing trials).
>
> First, I'd like to make sure that it is correct to use the following command
> to analyze such data.
>
> model = lmer(resp ~ A + B + C + B:C + (1|sub) + (1|item), data = xxx, family
> = "binomial")
>
> Second, for some instances, I got the warning message:
> In glm.fit(fr$X, fr$Y, weights = wts, offset = offset, family = family,  :
>  algorithm did not converge

That is an indication that your fixed-effects terms may be
overspecified.  To obtain starting estimates for the fixed-effects
parameters a model without random effects is fit initially.  It is the
equivalent of

glm(resp ~ A + B + C + B:C, data = xxx, family = "binomial")

that is failing so you may want to check the fixed-effects specification.

> and I got extremely small z values and all Pr(>|z|)s = 1.
>
> Is there anything I can do to solve this problem?
>
> Thank you.
>
> Best,
> Melissa
>
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