Re: LME- Comparing likelihood of two models

["F Z" <gerifalte28@hotmail.com>]

The book reccomends to use MLE for comparing competitive models with 
different fixed effects.  Basically you need to fit both models using method 
= "ML" and then use anova(m1,m2) to compare them.  That should take care of 
the problem.
Cheers

Francisco


> From: "Pravin" <jadhavpr@vcu.edu>
> To: <s-news@lists.biostat.wustl.edu>
> Subject: [S] LME- Comparing likelihood of two models
> Date: Tue, 28 Sep 2004 14:42:07 -0400
>
> Dear all,
>
>
>
> I seek input on the following issue: I have two competing models that I was
> hoping to compare based on the likelihood. I used REML method and upon
> performing anova(fiitedobject1,fittedobject2), the following *warning*
> message was obtained.
>
>
>
> ...Likelihood comparisons are not meaningful for objects fit using
> restricted maximum likelihood and with different fixed effects...
>
>
>
> It is true that my models differ only with respect to a single fixed effect
> parameter.
>
> I would like to know some references that address the underlying reason. I
> did perform internet search and looked at Mixed-effects modeling in S and
> S-Plus by Pinheiro and Bates but haven't understood the issue completely.
> There is some mention of it in the book while explaining the estimation
> methods. Are there any other references?
>
>
>
> Thanks,
>
>
>
> Pravin
>
>
>
> Pravin Jadhav
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