Re: [R] Doubt about nested aov output

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Mon 05 Sep 2005 - 09:31:42 EST

          Others may know the answer to your question, but I don't. However, since I have not seen a reply, I will offer a few comments:

  1. What version of R are you using? I just tried superficially similar things with the examples in ?aov in R 2.1.1 patched and consistently got F and p values.
  2. My preference for this kind of thing is to use lme in library(nlme) or lmer in library(lme4). Also, I highly recommend Pinheiro and Bates (2000) Mixed-Effects Models in S and S-Plus (Springer).
  3. If still want to use aov and are getting this problem in R 2.1.1, could you please provide this list with a small, self contained example that displays the symptoms that concern you? And PLEASE do read the posting guide! "http://www.R-project.org/posting-guide.html". It might increase the speed and utility of replies.

          spencer graves

Ronaldo Reis-Jr. wrote:

> Hi,
>
> I have two doubts about the nested aov output.
>
> 1) I have this:
>

>>anova.ratos <- aov(Glicogenio~Tratamento+Error(Tratamento/Rato/Figado))
>>summary(anova.ratos)

>
>
> Error: Tratamento
> Df Sum Sq Mean Sq
> Tratamento 2 1557.56 778.78
>
> Error: Tratamento:Rato
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 3 797.67 265.89
>
> Error: Tratamento:Rato:Figado
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 12 594.0 49.5
>
> Error: Within
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 18 381.00 21.17
>
> R dont make the F and P automatically, it is possible?
>
> I Like an output like this:
>
> Error: Tratamento
> Df Sum Sq Mean Sq F value Pr(>F)
> Tratamento 2 1557.56 778.78 2.929 0.197
>
> Error: Tratamento:Rato
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 3 797.67 265.89 5.372 0.0141
>
> Error: Tratamento:Rato:Figado
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 12 594.0 49.5 2.339 0.0503
>
> Error: Within
> Df Sum Sq Mean Sq F value Pr(>F)
> Residuals 18 381.00 21.17
>
> Why it not make automatic calculations? It is possible?
>
>
> 2) I can say that Error: Tratamento:Rato means an interaction between
> Tratamento and Rato? Normally the : represents an interaction, but in this
> output I think that it dont mean the interaction.
>
> Any explanation are welcome.
>
> Thanks
> Ronaldo
-- 
Spencer Graves, PhD
Senior Development Engineer
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Received on Mon Sep 05 09:39:58 2005

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