Re: [R] lmer BIC changes between output and anova

From: <lorenz.gygax_at_art.admin.ch>
Date: Fri 06 Oct 2006 - 12:27:56 GMT


The two models that you compare differ in their fixed effects. As far as lme had been concerned, the anova gave a warning because one should not compare two models differing in their fixed effects if they had been estimated with REML (Pinheiro & Bates, 2000).

I guess the issue is still the same using lmer (but anyone please correct me, if I am wrong) but perhaps the warning message is currently not implemented.

Regards, Lorenz
-
Lorenz Gygax
Centre for proper housing of ruminants and pigs Swiss Federal Veterinary Office
Agroscope Reckenholz-Tšnikon Research Station ART

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch]On Behalf Of Darren M. Ward
> Sent: Thursday, October 05, 2006 5:18 PM
> To: r-help@stat.math.ethz.ch
> Subject: [R] lmer BIC changes between output and anova
>
> list,
>
> i am using lmer to fit multilevel models and trying to use
> anova to compare the models. however, whenever i run the
> anova, the AIC, BIC and loglik are different from the
> original model output- as below. can someone help me out
> with why this is happening? (i'm hoping the output
> assocaited with the anova is right!).
>
> thank you,
>
> darren
>
> > unconditional<-lmer(log50 ~ 1 + (1 | Stream:Site) +
> (1|Stream), data)
> > summary(unconditional)
> Linear mixed-effects model fit by REML
> Formula: log50 ~ 1 + (1 | Stream:Site) + (1 | Stream)
> Data: data
> AIC BIC logLik MLdeviance REMLdeviance
> -138.8 -132.8 72.42 -150.4 -144.8
>
>
> > nosection<-lmer(log50 ~ 1 + meanlogATS + residuallogATS +
> (1 | Stream:Site) + (1|Stream), data)
> > summary(nosection)
> Linear mixed-effects model fit by REML
> Formula: log50 ~ 1 + meanlogATS + residuallogATS + (1 |
> Stream:Site) + (1 | Stream)
> Data: data
> AIC BIC logLik MLdeviance REMLdeviance
> -140.8 -130.7 75.4 -168.9 -150.8
>
>
> > anova(unconditional, nosection)
> Data: data
> Models:
> unconditional: log50 ~ 1 + (1 | Stream:Site) + (1 | Stream)
> nosection: log50 ~ 1 + meanlogATS + residuallogATS + (1 |
> Stream:Site) +
> unconditional: (1 | Stream)
> Df AIC BIC logLik Chisq Chi Df
> Pr(>Chisq)
> unconditional 3 -144.370 -138.294 75.185
>
> nosection 5 -158.861 -148.734 84.430 18.491 2
> 9.657e-05 ***
>
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>



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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Fri Oct 06 22:31:55 2006

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