[R] glm contrasts

[Natalie Holt]

Hi,

I have some data on the effect of cycle shape (categorical) and  
frequency (continuous) on the efficiency of muscle contraction. My  
minimum adequate model is:

m15<-glm(efficiency~cycle.shape*freq, family=quasipoisson)


However, I wish to know where significant differences lie between  
specific combinations of treatments. I guess I want an equivalent of a  
post hoc test following an ANOVA. Is there a way of doing this for 2  
explanatory variables with an interaction between them and the above  
error structure.

Mnay thanks,

Natalie