[R-sig-ME] comparing treatment with different skewness

[Nicholas Lewin-Koh]

Hi Maarten,
Without the random effects, you are basically
asking can you fit a model where the variance is a function of the
group.
So I would think you could do this using nlme,
ie somehthing like
library(nlme)
lme(y~T + X1, data=mydat,
weights=varPower(form=~1|group),random=~1|whatever)

However, without more information it is hard to say more than that.

Nicholas


> Message: 2
> Date: Thu, 3 Mar 2011 11:11:51 +0100
> From: Maarten de Groot <Maarten.deGroot at nib.si>
> To: <r-sig-mixed-models at r-project.org>
> Subject: [R-sig-ME] comparing treatment with different skewness
> Message-ID: <4D6F6967.8010303 at nib.si>
> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
> 
> Dear list,
> 
> I have a problem regarding choosing the distribution family for a mixed 
> model. I want to compare my response variable y with treatment A,B,C and 
> D. In each of the treatments the distribution of y is differently. Is 
> there a way to implement this in a mixed model?
> 
> Kind regards,
> 
> Maarten
> 
> 
>