[R] lme: model variance and error by group

[ONKELINX, Thierry]

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 op inbo.be
www.inbo.be

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> -----Oorspronkelijk bericht-----
> Van: r-help-bounces op r-project.org 
> [mailto:r-help-bounces op r-project.org] Namens Tursiops
> Verzonden: vrijdag 21 mei 2010 16:14
> Aan: r-help op 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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