library(vcd) # main effects model data(Arthritis) # define Better Arthritis$Better <- Arthritis$Improved > 'None' arth.mod1 <- glm(Better ~ Age + Sex + Treatment , data=Arthritis, family='binomial') Anova(arth.mod1) # diagnostic plots: "regression quartet" #setwd("c:/sasuser/catdata/R") #postscript(file="arthritis-diag1.eps", paper="special", height=6, width=6, onefile=TRUE, horizontal=FALSE) op <- par(mfrow=c(2,2)) plot(arth.mod1) par(op) #dev.off() library(car) # influence plot #postscript(file="arthritis-diag2.eps", paper="special", height=6, width=6, onefile=TRUE, horizontal=FALSE) influencePlot(arth.mod1, main="Arthritis data: influencePlot") #dev.off()