Dear R users,
I am currently analyzing a dataset using lme(). The model I use has the following structure:
model<-lme(response~Covariate+TreatmentA+TreatmentB,random=~1|Block/Plot,method="ML")
When I plot the residuals against the fitted values, I see a clear positive trend (meaning that the variance increases with the mean).
I tried to solve this issue using weights=varPower(), but it doesnīt change the residual plot at all.
How would you implement such a positive trend in the variance? Iīve tried glmmPQL (which works great with poisson errors), but using glmmPQL I canīt do model simplification.
Many thanks for your help!
Regards Chris.
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