I am interested in evaluating whether or not the joint effect of two independent variables on an outcome are additive. I want to be able to give something analogous to the Breslow-Day test of homogeneity, which evaluates effect modification on the multiplicative scale, but on the additive scale. I would also like to calculate the common Risk Difference across two strata. Does anyone know of any R package that has these functions, which focus on additive relationships in stratified analyses?
Cheers, Jens [[alternative HTML version deleted]] _______________________________________________ R-sig-Epi@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-epi