#
# Epage 137
#
# 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.
# 
#-----

# version$language == "R" for R version$language == NULL for SPlus

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

# transactions data
if(is.null(version$language) == FALSE) data(transact)
if(is.null(version$language) == FALSE)
   pairs(transact,gap=0.4,cex.labels=1.5,cex=0.5)  else
   pairs(transact)

m1 <- lm(Time~ T1 + T2, data=transact)

dm <- delta.method(m1,"b1/b2")

# compare this to the values obtained by the bootstrap in Chapter 4:
#
alpha = 0.95
nConf <- qnorm( 1 - (1-alpha)/2 )
print( dm$estimate - nConf * dm$se )
print( dm$estimate + nConf * dm$se )