[R] lme with/without varPower - can I use AIC?

[Dieter Menne]

Renaud,

> Obviously, from this definition, you won't get the same value for t.hat
> if you do:
> 
> PainW.lme<-lme(Pain~p+Treat*Spotter,data=saw,random=~p|Pat,
>              weights=varPower(form=~Pain))
> 
> or
> 
> pain <- Pain / 10
> PainW.lme<-lme(Pain~p+Treat*Spotter,data=saw,random=~p|Pat,
>              weights=varPower(form=~pain))
> 

Well, I do get the same. Or at least "almost", there must be some problem
with the algorithm:

Factor for Pain     Power 
*0.001               5.9
*0.1                 5.9 
*1                   5.9  // Orignal data
*2                   5.78 // Don't ask me about this!!!
*3 and all larger    6.56 



Dieter


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