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#
# Script for Assignment 14
#
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# Problem 14.1

# This problem is just interpreting the ANOVA table



# Problem 14.2

c05 <- c(1.62, 1.60, 1.62, 1.66)
c10 <- c(2.69, 2.66, 2.72, 2.73)
c15 <- c(3.56, 3.45, 3.65, 3.52)
c20 <- c(3.35, 3.18, 3.40, 3.06)

enthalpy <- c(c05, c10, c15, c20)
concentration <- as.factor( c(rep(5,4), rep(10,4), rep(15,4), rep(20,4)) )

m14.2 <- aov(enthalpy~concentration)
summary( m14.2 )

pairwise.t.test(enthalpy,concentration, p.adjust.method="bonferroni")

TukeyHSD(m14.2)



# Problem 14.3

crime  <- read.csv("http://oforsber.kvasaheim.com/courses/stat4073/data/crime.csv", header=TRUE)
vcrime <- crime$vcrime90
region <- crime$census4

mean(vcrime)
m14.3 <- aov(vcrime~region)
summary(m14.3)

png("figure143.png", height=500, width=600)
boxplot(vcrime~region, ylab="Violent Crime Rate (1990)")
dev.off()
TukeyHSD(m14.3)



# Problem 14.4

joints <- read.csv("problem144.csv", header=TRUE)
names(joints)
attach(joints)

m144 <- aov(cof~taper*length)
summary(m144)

mean(cof)
mean(cof[taper=="CPTi-ZrO2"])
mean(cof[taper=="TiAlloy-ZrO2"])

mean(cof[length=="short"])
mean(cof[length=="medium"])
mean(cof[length=="long"])

TukeyHSD(m144)

t.test(cof[length=="short"], cof[length=="medium"] )$p.value
t.test(cof[length=="short"], cof[length=="long"] )$p.value
t.test(cof[length=="medium"], cof[length=="long"] )$p.value