Re: [R] R-help Digest, Vol 32, Issue 26

From: Doran, Harold <HDoran_at_air.org>
Date: Wed 26 Oct 2005 - 23:15:50 EST


In addition to the response below, Doug Bates has talked about this on this list previously. I did

> RSiteSearch('bates degrees of freedom lmer')

The first one that came up has Doug's response to this question as well

Harold  

-----Original Message-----
From: r-help-bounces@stat.math.ethz.ch
[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Alan Cobo-Lewis Sent: Wednesday, October 26, 2005 8:53 AM To: r-help@stat.math.ethz.ch
Subject: Re: [R] R-help Digest, Vol 32, Issue 26

r-help@stat.math.ethz.ch on Wednesday, October 26, 2005 at 6:00 AM -0500 wrote:

Ronaldo,
Try Harold's suggestion. The df still won't agree, because lmer (at least in its current version) just puts an upper bound on the df. But that should be OK, because all those t tests are approximations anyways, and you can get better confidence intervals (credible intervals, whatever) by using the mcmcsamp() function that works with lmer() alan

>

"Doran, Harold" <HDoran@air.org> responded:
>
>
>>There is an issue with implicit nesting in lmer. In your lme() model
>>you nest block/irrigation/density/fertilizer. In lmer you need to do
>>something like (I dind't include all of your variables, but I think
>>the makes the point)
>>
>>lmer(yield~irrigation*density*fertilizer+(1|fertilizer:density)+(1|den
>>sity), data)
>>
>>Which notes that fertilizer is nested in density.
>>
>>Try this and then compare the results.
>
"Ronaldo Reis-Jr." <chrysopa@gmail.com>, wrote:
>
>>I make the correct model with aov, lme do compare with lmer.
>
>>But I cant make a correct model in lmer. Look that the aov and lme
>>results are similars, but very different from lmer. In aov and lme is
>>used the correct DF for each variable, in lmer it use a same DF for
all? Denom=54.
>

--
Alan B. Cobo-Lewis, Ph.D.		(207) 581-3840 tel
Department of Psychology		(207) 581-6128 fax
University of Maine
Orono, ME 04469-5742     		alanc@maine.edu

http://www.umaine.edu/visualperception

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Received on Wed Oct 26 23:36:46 2005

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