########## R script: mitsub ##########

# For doing a regression analysis of the
# Mitsubishi price/age data.

# Last changed: 24 SEP 2001

# Define function wait() for sending prompts
# to the screen. (Very useful for scripts such
# as this).

wait <- function()
{
        cat("Hit return to continue\n")
        ans <- readline()
        invisible()
}

# Read in data into data frame named 'mitsub'

mitsub <- read.table("mitsub.dat",header=T,sep=",")

price <- mitsub$price
age <-  mitsub$age

# Obtain and print some summary statistics

print(summary(mitsub))

wait()

# Draw graphics

hist(price)

wait()

boxplot(age)

wait()

boxplot(split(price,age))

wait()

plot(age,price,pch=1)

wait()

# Obtain a regression fit 

fit <- lm(price~age,data=mitsub)

# Add fitted line to plot

abline(fit$coef)

# Print summary of regression fit

wait()

print(summary(fit))

wait()

# Do some diagnostic plots

par(mfrow=c(2,3))
plot(fit)

########## End of mitsub ##########