pdf("kuehl_06_03.pdf")


city <- rep(1:3,each=12)
rate <- rep(seq(0.5,1.5,0.5),each=4,times=3)
zinc <- c(26.4,23.5,25.4,22.9,25.2,39.2,25.5,31.9,26.0,44.6,35.5,38.6,
          30.1,31.0,30.8,32.8,47.7,39.1,55.3,50.7,73.8,71.1,68.4,77.1,
          19.4,19.3,18.7,19.0,23.2,21.3,23.2,19.9,18.9,19.8,19.6,21.9)

barley <- data.frame(city,rate,zinc)

attach(barley)

city <- factor(city,levels=1:3,labels=c("A","B","C"))
rate <- factor(rate,levels=seq(0.5,1.5,0.5),ordered=T)

tapply(zinc,list(city,rate),mean)

barley.mod1 <- aov(zinc ~ city + rate + city:rate)
summary(barley.mod1)

summary(barley.mod1,split=list(rate=list(linear=1,quadratic=2)))

dev.off()