[R] glmmPQL and random factors

Per Toräng Per.Torang at ebc.uu.se
Tue Sep 14 11:06:56 CEST 2004


I have tested the effect of two treatments on fruit set, i.e. fruits per plant. 
The treatments had two levels each giving four different treatment 
combinations. Forty separated plots were subjected to one of the treatment 
combinations so each combination was replicated ten times. I intend to analyze 
my data using the glmmPQL procedure in the following way.

glmmPQL(Fruit.set~Treat1*Treat2+offset(log10(No.flowers)), random=~1|Plot, 
family=poisson, data=....)

Plot is supposed to be nested in (Treat1*Treat2).
Is this analysis suitable? Moreover, what is the meaning of typing 
random=~1|Plot compared to random=~Treat1*Treat2|Plot?

Per Toräng
per.torang at ebc.uu.se

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