vif function for lmer object

[Jane]

Dear all,

I'm trying to look at multi-collinearity for mixed linear models. I used lmer for the model. The vif function from "car" package deal with only an lm or glm object. I am looking for an equivalent function of VIF which works with lmer objects. 

I searched several R-help lists and stackoverflow, but haven't found anything that could solve the problem.

Does anyone have any ideas?

I would really appreciate!

Jane

[Dave Harris]

I haven't checked if the code is correct, but someone posted this online. The first function claims to estimate VIF for lmer objects. You may need to make some tweaks if you're using a newer version of lme4. https://github.com/aufrank/R-hacks/blob/master/mer-utils.R

You can also diagnose some issues manually by looking at the covariance among some of your estimates using `vcov` and `VarCorr`.

Hope this helps.

Dave

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[Anna Steel]

There was a package called AED written by Zuur et al and shared as part of their 2009 book "Mixed effects models and extensions in ecology with R" (blue-purple one with penguins on the cover, also available from our library as an e-book). The package included a function called 'corvif' that helps identify variables with high inflation factors for GLMMs. The authors no longer update AED for new versions of R, but you can download the code at their website  http://www.highstat.com/book2.htm.

I seem to recall I had to make a few modifications to make it run properly, but it worked like a charm after the tweeks. Plus the book gives you guidance on how to properly use the function.

Hope that helps!

Anna

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Anna Steel, PhD candidate

Biotelemetry Laboratory
Ecology Graduate Group

University of California, Davis

 

530-828-2328
AnnaE...@gmail.com