I have found the problem and a solution.
The problem comes from the functions addterm.glm() and dropterm.glm()
from MASS package. They use extractAIC() without transmitting the ...
argument:
aic <- aic + (extractAIC(object, k = k)[2L] - aic[1L])
I replace the call with:
aic <- aic + (extractAIC(object, k = k, ...)[2L] - aic[1L])
and I create dropterm.glm() and addterm.glm() in global environnement.
I add:
dropterm <- dropterm.lm <- dropterm.glm
addterm <- addterm.lm <- addterm.glm
I copy also stepAIC from MASS package to global environnement.
I detach MASS package, and it works:
> stepAIC(G1, criteria="AICc", steps = 1)
Start: AIC=70.06
x ~ A + B
Df Deviance AIC
- A 1 48.506 68.355
<none> 47.548 70.055
- B 1 57.350 70.867
Now stepAIC can use AICc
Marc
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