#
# Epage 93
#
# Written by:
# -- 
# John L. Weatherwax                2009-04-21
# 
# email: wax@alum.mit.edu
# 
# Please send comments and especially bug reports to the
# above email address.
# 
#-----

library(alr3)
data(transact)
attach(transact)

A = 0.5 * ( T1 + T2 )
D = T1 - T2 

m1 = lm(Time~ T1 + T2)
m2 = lm(Time~ A + D )
m3 = lm(Time~ T2 + D)
m4 = lm(Time~ T1 + T2 + A + D)

coef(m1)
coef(m2)
coef(m3)
coef(m4)