#
# 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(DAAG)

cities$have = factor( ( cities$REGION == "ON" ) | ( cities$REGION == "WEST" ) )

#postscript("../../WriteUp/Graphics/Chapter6/prob_1_direct_plot.eps", onefile=FALSE, horizontal=FALSE)
plot( POP1996 ~ POP1992, data=cities, col=as.integer(cities$have) )
#dev.off()

#postscript("../../WriteUp/Graphics/Chapter6/prob_1_log_plot.eps", onefile=FALSE, horizontal=FALSE)
plot( log(POP1996) ~ log(POP1992), data=cities, col=as.integer(cities$have) )
#dev.off()

# View the summary plots for the two models:
# 
cities.lm1 = lm( POP1996 ~ have + POP1992, data=cities )
oldpar = par(mfrow=c(1,4))
plot( cities.lm1 )
par(oldpar)

cities.lm2 = lm( log(POP1996) ~ have + log(POP1992), data=cities )
oldpar = par(mfrow=c(1,4))
plot( cities.lm2 )
par(oldpar)