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#
#  Script: 31 March 2011 (preliminary)
#
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# Today:
#
#   ** Miscellaneous helpful items
#


crime <- read.csv("http://courses.kvasaheim.com/stat40x3/data/crime.csv", header=TRUE)

names(crime)
summary(crime)



m0 <- glm( gspcap00 ~ gspcap90 * vcrime90, family=gaussian(link=identity), data=crime )
summary(m0)

m1 <- glm( gspcap00 ~ gspcap90 + vcrime90, family=gaussian(link=identity), data=crime )
summary(m1)



# Functions in the y-variable

m2 <- glm( I(gspcap00-gspcap90) ~ vcrime90, family=gaussian(link=identity), data=crime )
summary(m2)





# The with() function

with( crime, cor(vcrime90, vcrime00) )





# The indentify() function

plot( I(vcrime00-vcrime90)~gspcap90, data=crime)
abline(h=0)
with(crime, identify( gspcap90, I(vcrime00-vcrime90), n=10, pos=T, labels=scode) )


# The text() function

plot( I(vcrime00-vcrime90)~gspcap90, data=crime, type="n")
with(crime, text( I(vcrime00-vcrime90)~gspcap90, labels=scode) )