[R-sig-ME] Post-hoc test and Cook's distance vs. leverageplot for glmer from package lme4

[Mario Garrido]

Hi,
thanks for the responses. I will explore in deep what both of you say.
I will be back once I got an answer...or more questions!




2015-04-16 23:09 GMT+03:00 Ben Bolker <bbolker at gmail.com>:

> Mario Garrido <gaiarrido at ...> writes:
>
> >
> > Hi,
> >
> > My name's Mario Garrido, a postdoctoral student in Biology. I am
> relatively
> > new with r and despite I find it brilliant I am having some difficulties
> in
> > finding some functions and interpreting the syntaxes.
> >
> > At the moment I am working on a GLZM model which fits a Poisson
> > distribution. I am having some problems with two issues
> >
> > 1.     after calculating Akaike weights, my best model is one including a
> > 4-way interaction term. It is the following:
> >
> > model7<-glmer(active~ treatment*daytype*time*age+(1|
> > indiv),family=poisson(link=log),nAGQ=1)
> >
> > Is there any function or package to perform a Post hoc test to know which
> > subset of 2- and 3-way interaction terms have more influence on the
> model?
>
>   It strikes me that this is a somewhat difficult question
> conceptually, as well as computationally.  How are you dealing
> with the issues of marginality?  (See Venables "Exegeses on linear
> models", available by internet-searching, for a discussion of
> marginality ...)  In other words, how do you define what a
> 2- or 3-way interaction term means?
>
>  *If* you can define what you mean (e.g. if simply setting the
> parameters related to a specific lower-level interaction to zero
> makes biological or scientific sense), then you could drop the
> terms and look at the difference in AIC or log-likelihood, and
> use some sort of multiple comparisons to deal with the post-hocness
> of it all.
>
> >
> > 2.     In addition, I find how to compute Cook's distance both for the
> > function glmer and for the function lmer using the package influence.ME.
> > This package also allow to make some graphs but, is there any
> > package or function to do it and obtain a plot similar to this:
> > https://climateaudit.files.wordpress.com/2012/09/lew_cooks-distance1.png
> ?
> >
>
>   Have you found a way to compute (or define) leverage for a GLMM?
> (Maybe that's what you're asking for.)
>
>   Ben Bolker
>
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