# R doce for ex 1.28 p37
crime=read.table("C:/Users/Mihinda/Desktop/CH01PR28.txt", header=0) #the data file
y <- crime[,1]
x <- crime[,2]
par(mfrow=c(3,1))
plot(x, y)
fit = lm(y ~x)
summary(fit)
yhat = predict.lm(fit)
lines(x,yhat)
anova(fit)
plot(fitted(fit),residuals(fit))
qqnorm(residuals(fit))
#prdicting EY at a given value x0
x0 <- data.frame(x=74)
predict(fit, x0)
#CI for the mean of Y at x=x0
predict(fit, x0, interval="confidence", level=0.95)
# prediction interval for a new Y at x = x0
predict(fit, x0, interval="prediction", level=0.95)
#Bonferroni simultaneous PI at k given points
x0 <- data.frame(x=c(75, 80))
k <- dim(x0)[1]
alpha <- 0.05
predict(fit, x0, interval="prediction", level=1-alpha/k)