#
# Epage 
#
# 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(jevons)
attach(jevons)

# a scatterplot matrix
#
postscript("../../WriteUp/Graphics/Chapter5/prob_6.eps", onefile=FALSE, horizontal=FALSE)
plot( Age, Weight ) 
dev.off()

postscript("../../WriteUp/Graphics/Chapter5/prob_6_SD_vs_age.eps", onefile=FALSE, horizontal=FALSE)
plot( Age, SD )
dev.off()

# we will fit :
#
weight_vs_age2 <- lm( Weight ~ Age, weights = 1 / ( n / SD^2 ) )

s <- summary(weight_vs_age2)
a <- anova(weight_vs_age2)

sigma2 <- s$sigma^2

X2 = a$"Sum Sq"[2] / 1 

p_prime = 2