[R] How to calculate confidence interval for each level of a binary explanatory variable when there is interaction

Zsuzsanna Papp Zsuzsanna.Papp at shaw.ca
Tue Nov 29 04:45:57 CET 2011

I have a logistic regression model with several categorical explanatory
variables and one interaction term (between two binary variables, named
A and B). I know how to calculate the odds ratios for the different
levels of A and B (for A=1, e.g., I need to add the coeff for A to coeff
for A*B, then exponentiate), but how do I get a confidence interval for
this OR? I can get the confidence interval using "confint" for A (when
A=0), and B (when B=0) and A*B, but I would like to get the confidence
interval for the OR of level 1 of A and for level 1 of B.

Thank you for any advice or question asking for clarification.

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