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difficulties getting coef() to work in some lmer() calls
2 messages · David Park, Douglas Bates
9 days later
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 George Washington University Monroe Hall 2115 G Street, NW Washington, D.C. 20052 http://home.gwu.edu/~dkp/ <http://home.gwu.edu/%7Edkp/> Direct: (202) 994-2331 Dept: (202) 994-6290 Fax: (202) 994-7743 "The great tragedy of Science - the slaying of a beautiful hypothesis by an ugly fact." -- Thomas H. Huxley [[alternative HTML version deleted]]
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