#
# EPage 241
#
# 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.
# 
#-----

save_plots = F

library(DAAG)
library(MASS)

cuckoos.rlm_a = rlm( length ~ breadth, data=cuckoos ) # one model
cuckoos.rlm_b = rlm( length ~ breadth + species, data=cuckoos ) # different intercepts and the same slope 
cuckoos.rlm_c = rlm( length ~ breadth + species + breadth:species, data=cuckoos ) # different intercepts and different slopes 

anova( cuckoos.rlm_a, cuckoos.rlm_b, cuckoos.rlm_c )

# look for outliers:
if( save_plots ){ postscript("../../WriteUp/Graphics/Chapter7/prob_6_plot.eps", onefile=FALSE, horizontal=FALSE) }
plot( cuckoos.rlm_b, which=1 )
if( save_plots ){ dev.off() }

# look at the coefficients:  
summary( cuckoos.rlm_b )