d = read.table("exmp11-11.txt",header=TRUE,sep=",")
d$Treat = as.factor(d$Treat)
d$Brand = as.factor(d$Brand)
plot(as.vector(d$Treat),d$Response)
for(j in 1:3)
  lines(1:4,d$Response[d$Brand==j])
        
fit = aov(Response~Brand+Treat,data=d)
summary(fit)
qqnorm(fit$res);qqline(fit$res)
plot(fit)
plot(TukeyHSD(fit,which="Treat"))