Hello R-users,

My first consult is that I would like to tackle the relationship between a
dependent variable and four environmental factors using a glm binomial
model. The problem is that I want to test the interaction between factors
too and I would like to learn some way to do it automatically.

Now, my syntax is, for instance:

E1<-glm(formula = (ENF/TOT)~VAR1+VAR2+VAR3+VAR4, family = binomial, data =
DATA, weights = TOT)

And I would like to add pair interactions at least: VAR1*VAR2+VAR1*VAR3,
etc... for all possible combinations.

My second question is that the model does not show me the R-squared neither
using summary(E1) nor writing simply E1.


Thank you very much!

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