library(car) # for Anova() data(UCBAdmissions) UCB.df <- as.data.frame(UCBAdmissions) berk.mod1 <- glm(Admit=="Admitted" ~ Dept, data=UCB.df, weights=UCB.df$Freq, family="binomial") Anova(berk.mod1, test="Wald") summary(berk.mod1) berk.mod2 <- glm(Admit=="Admitted" ~ Dept+Gender, data=UCB.df, weights=UCB.df$Freq, family="binomial") Anova(berk.mod2, test="Wald") summary(berk.mod2) library(effects) ## load the effects package berk.eff2 <- allEffects(berk.mod2) # plot main effects plot(berk.eff2) # plot 'interaction' -- produces a harmless warning plot(effect('Dept:Gender', berk.mod2), multiline=TRUE)