# This program produces the output and tables for
# Body Fat Example, NKNW 4th ed Table 7.1
# Objective:
# 1. Compute and Interprete Extra Sum of Squares
# 2. Decomposition of SSR in ANOVA
# Created by C. Andy Tsao. 060508

t<-matrix(scan("CH07TA01.DAT"),ncol=4,byrow=T)
dt<-data.frame(x1=t[,1],x2=t[,2],x3=t[,3],y=t[,4])
attach(dt)  # Default dt data.frame

m123<-lm(y~x1+x2+x3);
summary(m123);
anova(m123);

m1<-lm(y~x1);
summary(m1);

m12<-lm(y~x1+x2);
summary(m12);
anova(m12);

m21<-lm(y~x2+x1);
summary(m21);
anova(m21);

m132<-lm(y~x1+x3+x2);
summary(m132);
anova(m132);
# Pay attention to the identity t^2 = F