Have a look at ?varClasses. You could you something like varIdent(form ~
1|areatrai) or varExp(form = ~areatrai)
R-sig-mixed-models is a better list for this kind of questions.
Thierry
------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium
Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx at inbo.be
www.inbo.be
To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data.
~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] Namens Tursiops
> Verzonden: vrijdag 21 mei 2010 16:14
> Aan: r-help at r-project.org
> Onderwerp: [R] lme: model variance and error by group
>
>
> Hello
> I am trying to reproduce a mixed regression model published
> in (J Evol Biol 12:94-102) with PASW 17.03. The authors used
> SAS to fit the model using the following syntaxis:
>
> proc mixed nobound;
> class area individ trait;
> model a = side trait area side*trait side*area
> trait*area/ddfm = satterthwaite solution; random intercept
> side/subject = individ group = areatrai; repeated/local =
> quad(areatrai) subject = individ; run;
>
> The model specifies separate variance components and error
> variances for the grouping "areatrai" variable. This is
> indicated by "group= areatrai"
> and "local > quad (areatrai)", respectively.
>
> Since I currently have no access to SAS and this part of the
> analysis is absolutely central to my research, I would be
> very grateful if someone can tell whether it is possible to
> model the variance and error by group using lme or any other
> R package for linear mixed models.
>
> Any help will be much appreciated.
>
> Thanks
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/lme-model-variance-and-error-by-
> group-tp2226207p2226207.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
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