#' --- #' title: "Cowles data: Logistic regression" #' author: "Michael Friendly" #' date: "21 Jan 2015" #' --- library(effects) ## load the effects package library(car) ## for Anova: type II tests data(Cowles) #' ## Main effects model mod.cowles0 <- glm(volunteer ~ sex + neuroticism + extraversion, data=Cowles, family=binomial) summary(mod.cowles0) Anova(mod.cowles0) #' ## Test all interactions mod.cowles1 <- glm(volunteer ~ (sex + neuroticism + extraversion)^2, data=Cowles, family=binomial) summary(mod.cowles1) Anova(mod.cowles1) #' ## Add one interaction mod.cowles <- glm(volunteer ~ sex + neuroticism * extraversion, data=Cowles, family=binomial) summary(mod.cowles) anova(mod.cowles0, mod.cowles, mod.cowles1)