[R-sig-ME] complex residual variance

[ONKELINX, Thierry]

Not in lmer(). But you can do it with lme() from the nlme package.

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-sig-mixed-models-bounces at r-project.org 
> [mailto:r-sig-mixed-models-bounces at r-project.org] Namens Sven 
> De Maeyer
> Verzonden: maandag 31 mei 2010 15:47
> Aan: r-sig-mixed-models at r-project.org
> Onderwerp: [R-sig-ME] complex residual variance
> 
> Hi all,
> 
> I'm not a frequent user of Lme4 and I have the habit to use 
> mlwin for multilevel analyses. Nevertheless I'm willing to 
> master lme4 further.
> 
> In my research I'm often faced with the situation where level 
> 1 variance (or residual variance in the mixed effects
> framework) isn't constant. E.g. I have longitudinal data on 
> children, with multiple measurements (observations) of these 
> children at a certain moment. As children get older these 
> measurements seem to vary more and more. So the residual 
> variance itself is a function of time. As a consequence there 
> is heteroscedasticity.  Is there a possibility to explicitly 
> model this in lme4? I know how to do it in mlwin, but is it 
> possible in lmer?
> 
> With kind regards
> 
> Sven De Maeyer
> 
> _______________________________________________
> R-sig-mixed-models at r-project.org mailing list 
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> 

Druk dit bericht a.u.b. niet onnodig af.
Please do not print this message unnecessarily.

Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer 
en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is
door een geldig ondertekend document. The views expressed in  this message 
and any annex are purely those of the writer and may not be regarded as stating 
an official position of INBO, as long as the message is not confirmed by a duly 
signed document.