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2003 May 22
1
[R ] Query : problems with the arithmetic operator "^" with function "lme"
...quot; rate ~ (pressure + pressure^2 +
pressure^3 + pressure^4) * QB " . "^" is a problem !
So, we fit the model like this, including two matrices, for the fixed
effects and the random effects:
>Dialyzer$PressureA<-cbind(Dialyzer$pressure,...,Dialyzer$pressure^4)
>Dialyzer$PressureB<-cbind(Dialyser$pressure,Dialyzer$pressure^2)
Now, we fit the same model like this:
>fm3Dial.lme<-lme(rate~(PressureA)*QB,
+ Dialyzer,~PressureB,weights=varPower(form=~pressure))
We obtain:
Linear mixed-effects model fit by REML
Data: Dialyzer
Log-restricted-likelihood: -309.50...