Try this:

coef(fm$modelStruct$varStruct, uncons = FALSE)

On Fri, Oct 15, 2010 at 11:42 AM, Hoai Thu Thai <hoai-thu.thai@inserm.fr>wrote:

> Dear R-Users,
>
> I have a question concerning extraction of parameter estimates of variance
> function from lme fit.
>
> To fit my simulated data, we use varConstPower ( constant plus power
> variance function).
>
> fm<-lme(UPDRS~time,data=data.simula,random=~time,method="ML",weights=varConstPower(fixed=list(power=1)))
> I extract the results of this function by using the following codes:
> y<-summary(fm)
> x<-y$modelStruct$varStruct
> > x
> Variance function structure of class varConstPower representing
>       const        power
> 1.184535e-15 1.000000e+00
>
> These are the constants and power that apppear in the summary(fm), and that
> I want to extract.
> Hower I got different value of const when extracting from x:
>
> > x$const
>    const
> -34.36943
>
> Does anyone know why there is such difference and how to extract the
> expected value (1.184535e-15) ?
>
> Thanks in advance for your help.
>
> Thu
>
>
> ---
>
> THAI Hoai Thu
> INSERM U738 - Université Paris 7
> 16 rue Henri Huchard
> 75018 Paris, FRANCE
> Tel: 01 57 27 75 39
> Email: hoai-thu.thai@inserm.fr
>
> ______________________________________________
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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.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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