[R] differences between aov and lme

[Prof Brian Ripley]

The way you describe this, it would appear to be B/I/V, not B/V/I.

>From the footer:

> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Had you given us access to the data, it would have been much easier to 
answer the question: if you need further help please do so.


On Wed, 22 Nov 2006, domerg wrote:

> Hi,
>
> we have a split-plot experiment in which we measured the yield of crop
> fields. The factors we studied were:
>
> B : 3 blocks
> I : 2 main plots for presence of Irrigation
> V : 2 plots for Varieties
> N : 3 levels of Nitrogen
>
> Each block contains two plots (irrigated or not) . Each plot is divided
> into two secondary parcels for the two varieties.
> Each of these parcels is divided into three subplots corresponding to
> three ordered levels of nitrogen.
>
> We found in Venables & Ripley  (Modern Applied Statistics with S-plus,
> 3rd edition) the multistratum model for the same type of dataset but for
> three levels (without the "Irrigation" partition):
> aov(Y~N*V+Error(B/V), qr=T)
>
> which we adapted to our model:
> aov(Y~N*V*I+Error(B/V/I))
>
> In Pinheiro & Bates (Mixed-effect models in S and S-plus) and as we saw
> in the message "Re: lme and lmer syntax from Ronaldo Reis-Jr, Wed 26 Oct
> 2005", we fitted also the mixed model :
> lme(Y~N*V*I, random~1|B/V/I)
>
> On a random simulated response Y, we didn't obtain similar results -
> only one factor with the same F-value - from the "aov" function
> and the "lme" one (oppositely  to the  example used by Venables & Ripley
> and Pinheiro & Bates).
>
> Is there a mistake in one of our two models or an explanation of this
> difference?
>
> Thanks a lot in advance.
>
>
> Caroline Domerg and Frederic Chiroleu
> UMR 53 PVBMT (Peuplements Vegetaux et Bio-agresseurs en Milieu Tropical)
> CIRAD
> Pôle de Protection des Plantes (3P) - Saint-Pierre
> Ile de la Réunion
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595