Could we do backward elimination with mixed model using lmer

Question

I used the following syntax for the mixed model and then step but it did not work.

Does it normally work like this or I actually can not use backward elimination with lmer? Thanks!

fullmodel<-lmer(Eeff~NDF+ADF+CP+NEL+DMI+FCM + (1|Study),data=na.omit(phuong))
step(fullmodel, direction = "backward", trace=FALSE ) 

Answer 1

You can do this with lmerTest package:

library(lmerTest)
step(fullmodel)

After testing this function with my rather complex data, it does seem to produce feasible model alternatives.

Answer 2

You could do it, just not with the step function. Since your model is just additive it shouldn't take that long to do by hand.