[R] Schmera: a question on R software

[Torsten Hothorn]

On Wed, 18 Oct 2006, SCHMERA Dénes wrote:

> Dear All,
>
> I would like to run a generalized linear mixed model with the software R (one categorical predictor, one random factor, the distribution of the dependent variable is binomial, and the link is logit). Thereafter, I would like to perform multiple comparisons (post hoc test) among the groups of the categorical predictor.
>
> Is it possible with the software R?
>

yes and no. There is the `multcomp' package available but the CRAN version 
is limited to linear models (more or less). However, I'm currently working 
on a re-implementation which has solutions for your problem and much 
more :-)

For the time being, the development version is available from

 	http://www.imbe.med.uni-erlangen.de/~hothorn/multcomp2

The basic steps would be as follows:

### fit logistic regression model
> my.glm <- glm(response ~ myfactor, data = <mydata>, family = binomial())
### set up linear hypothesis for coef(my.glm) corresponding to all-pair 
### comparisons
> library("multcomp2")
> gh <- glht(my.glm, linfct = mcp(myfactor = "Tukey"))
### simultaneous confidence intervals with plots
> confint(gh)
> plot(confint(gh))

Hope that helps.

Torsten

> Are traditional methods of multple comparisons (for instance Tukey test) adequate for this purpose or not? Does Tukey test consider the binomial dsitribution of the dependent variable and the logit link?
>
> I am waiting for your answer,
> Denes Schmera
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> 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.
>