# les inn data fra eksempel 11.15 i boken
d = read.table("http://www.uio.no/studier/emner/matnat/math/STK2120/v14/exmp11-15.txt",header=TRUE,sep=",",
colClasses=c("numeric","factor","factor"))

# plott data
plot(as.vector(d$Brand),d$Power)
for(j in 1:4)
  lines(1:5,d$Power[d$Block==j])
        
# toveis anova
fit = aov(Power~Brand+Block,data=d)
summary(fit)
plot(fit)

# multippel sammenligning p? merke
TukeyHSD(fit,which="Brand")
plot(TukeyHSD(fit,which="Brand"));abline(v=0)