Re: [R] difficulties getting coef() to work in some lmer() calls

From: Douglas Bates <bates_at_stat.wisc.edu>
Date: Wed, 12 Dec 2007 13:57:04 -0600

On Dec 3, 2007 1:45 PM, David Park <dkp_at_gwu.edu> wrote:
> I'm working with Andrew Gelman on a book project and we're having some
> difficulties getting coef() to work in some lmer() calls.
>
> Some versions of the model work and some do not. For example, this works
> (in that we can run the model and do coef() from the output):
>
> R2 <- lmer(y2 ~ factor(z.inc) + z.st.inc.full + z.st.rel.full + (1 + factor(
> z.inc) | st.num), family=binomial(link="logit"))
>
> But this does not (the model runs but coef() doesn't work):
>
> R3 <- lmer(y2 ~ factor(z.inc) + z.st.inc.full + z.st.rel.full + (1 + z.inc |
> st.num ), family=binomial(link="logit"))
>
> We get the following error:
> Error in coef(R3) : unable to align random and fixed effects

Which indicates that the coefficients being estimated for each level of st.num do not correspond to any of the fixed-effects coefficients, hence the coef method, in the sense that it is used in nlme and lme4, cannot be applied.

You will need to change the fixed-effects specification so that it includes z.inc. This may mean modifying the contrasts from factor(z.inc). I would suggest switching to polynomial contrasts then replacing the linear term by z.inc

> The data are at
> http://www.stat.columbia.edu/~gelman/temp/lmerexample.txt<http://www.stat.columbia.edu/%7Egelman/temp/lmerexample.txt>
> The file to read the data are at:
> http://www.stat.columbia.edu/~gelman/temp/lmerexample.R<http://www.stat.columbia.edu/%7Egelman/temp/lmerexample.txt>
>
> Any help would be appreciated.
>
> David K. Park
>
> --
> David K. Park
> Visiting Researcher (Fall 2007 / Spring 2008)
> Applied Statistics Center
> Columbia University
> 1016 Social Work Bldg
> (Amsterdam Ave. at 122 St.)
> New York, NY 10027
>
> Assistant Professor
> Department of Political Science
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> 2115 G Street, NW
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> http://home.gwu.edu/~dkp/ <http://home.gwu.edu/%7Edkp/>
>
> Direct: (202) 994-2331
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>
> "The great tragedy of Science - the slaying of a beautiful hypothesis
> by an ugly fact."
> -- Thomas H. Huxley
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Wed 12 Dec 2007 - 20:02:57 GMT

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