#
# EPage 215
#
# 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.
# 
#-----

#install.packages("MPV")

library(lattice) # needed for xyplot 
library(DAAG)
library(MPV)

set.seed(0)

n_pts = 10000
x1 = runif(n_pts)
#x2 = rbinom(n_pts, 1, 1-x1)
#x2 = rbinom(n_pts, 1, x1)
x2 = rbinom(n_pts, 1, 0.5)

y = 5 * x1 + x2 + rnorm(n_pts, sd=0.1)

y.lm = lm( y ~ factor(x2) )
coef(y.lm)

y.lm2 = lm( y ~ x1 + factor(x2) )
coef(y.lm2)