2.112 Dangers of not looking at a plot. Table 2.1 (page 122) presents four sets of data prepared by the statistician Frank Anscombe to illustrate the dangers of calculating without first plotting the data.²²

1. (a) Use x to predict y for each of the four data sets. Find the predicted values and residuals for each of the four regression equations.

2. (b) Plot the residuals versus x for each of the four data sets.

3. (c) Write a summary of what the residuals tell you for each data set, and explain how the residuals help you to understand these data.