[R-sig-ME] thoughts on variable importance

[Farrar, David]

Sorry yes.   I think my coffee had not taken effect.  The broad issue is comparison of variable importance when some variables have been modeled as fixed and others as random.   In my case the variables of most interest were modeled as fixed and some nuisance variables (as I saw them) were modeled as random.   I thought this was crude but possibly good enough for the situation, but I wondered if there was an interest in discussing this, or there are some more refined methods that I might have considered.  The actual analysis is already done and published some time ago.   I didn't want to go into more detail because I did not want to focus on the modeling.   I intended to be a little vague in order to cast a wide net.  

-----Original Message-----
From: Ben Bolker [mailto:bbolker at gmail.com] 
Sent: Monday, March 26, 2018 8:54 AM
To: Farrar, David <Farrar.David at epa.gov>
Cc: r-sig-mixed-models at r-project.org
Subject: Re: [R-sig-ME] thoughts on variable importance

Methodology questions are fine, but can you spell out your question a bit more?

On Mon, Mar 26, 2018 at 8:34 AM, Farrar, David <Farrar.David at epa.gov> wrote:
> There is probably some tendency for studies to be planned so that the variables thought to be most important can be evaluated as fixed effects, as I did.
> For analysis of a small field environmental field study, I eyeballed the BLUPs for a few nuisance variables, and noted that they did not suggest effects as large as for those variables that interested us most.   Thoughts?
> My apology if a methodology question is not favored here.   I did not think it was a question about introductory mixed models.
> Regards,
> David
>
> David Farrar, Ph.D., Biostatistician
> USEPA ORD NCEA BRAB Cincinnati, OH
>
>
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