#
# 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.
# 
#-----

if(is.null(version$language) == FALSE){ 
  require(alr3)
}else{
  library(alr3)
}

data(UN3)

UN3$logPPgdp <- log(UN3$PPgdp)
m0 <- lm( ModernC ~ logPPgdp+Change+Pop+Fertility+Frate+Purban, data=UN3 )
s0 <- summary(m0)

# use avp (added variable plot) found in the car package
library(car)

postscript("../../WriteUp/Graphics/Chapter9/prob_9_avp.eps", onefile=FALSE, horizontal=FALSE)
avp(m0, ask=FALSE, one.page=TRUE, identify.points=FALSE)
dev.off()

ind1 <- match( max(UN3$Pop), UN3$Pop ) # 25
#UN3$Pop[ind1] <- 0 # used to find the second largest element
ind2 <- match( max(UN3$Pop), UN3$Pop ) # 50 
UN3[c(25,50),]

# look for the point that has the largest value of Change:
#
ind1 <- match( max(UN3$Change), UN3$Change ) # 77
UN3[ind1,]

ti <- rstudent(m0)

ind1 <- match( max(ti), ti ) # 28 
ti[ind1] <- 0
ind2 <- match( max(ti), ti ) # 76
ti[ind2] <- 0
ind3 <- match( max(ti), ti ) # 125
ti[ind3] <- 0
ind4 <- match( max(ti), ti ) # 65 

posOut <- c(28,76,125,65)
n <- length(UN3$Pop)
pprime <- length(m0$coefficients)
  
n * 2 * ( 1 - pt( ti[posOut],n-pprime-1) )

DI <- cooks.distance( m0 )
plot(DI)