pdf("caffeine1.pdf")

caffeine <- read.fwf("C:\\data\\caffeine.dat", width=c(1,5,8),
col.names=c("subject", "dose", "endtime"))

fdose <- factor(caffeine$dose, levels=c(0,5,9,13))
levels(fdose) <- c("0mg","5mg","9mg","13mg")

caffeine1 <- data.frame(caffeine, subject=factor(caffeine$subject), fdose)

attach(caffeine1)

caffeine1.rbd <- aov(endtime ~ subject + fdose)

summary(caffeine1.rbd)

interaction.plot(subject,fdose,endtime)

caffeine.res <- residuals(caffeine1.rbd)

hist(caffeine.res)

dev.off()