# Illustration of Figure 10.7 in the text


CanPrestige1 <- read.table("c:/temp/prestige.txt",header=T)
names(CanPrestige1)


 # make a new education variable
CanPrestige1$ed2 <- 2*CanPrestige1$education


 # center variables

CanPrestige1$educationc <- CanPrestige1$education -mean(CanPrestige1$education)

CanPrestige1$ed2c <- CanPrestige1$ed2 - mean(CanPrestige1$ed2)

CanPrestige1$prestigec <- CanPrestige1$prestige -mean(CanPrestige1$prestige)


 # coefficients are different

summary(lm(prestigec ~ educationc -1, data = CanPrestige1))

summary(lm(prestigec ~ ed2c -1, data = CanPrestige1))


 # sums of squares and related quantities are not different

anova(lm(prestigec ~ educationc -1, data = CanPrestige1))

anova(lm(prestigec ~ ed2c -1, data = CanPrestige1))