# R script for linear regression using lm() function.
# Data frame "faithful" in R contains 272 observations of
# eruption duration (eruptions) in minutes and subsequent
# waiting time until next eruption (waiting) in minutes.

attach(faithful)  #  Example data set contained in R.
head(faithful)

# Calculate regression model.
results=lm(waiting~eruptions)

# Print summary of the fitted model.
summary(results)

# Plot the data and fitted model.
plot(eruptions,waiting,type="p")    #  Scatterplot.
abline(results)                     #  Add regression line to scatterplot.

# Open new graphics window and print diagnostic plots.
X11()   # quartz()in Mac 
layout(matrix(1:4,2,2))
plot(results)                       #  Diagnostic plots for evaluating
                                    #  the regression model.