Prepare the report card. Refer to the previous exercise. One way to compare cities with respect to the amount of open space that they have is to compare the actual open space with the open space that is predicted by the least-squares regression line.
Using the data and the regression line from the previous exercise, compute the difference between the actual open space and the predicted open space for each city. Cities with positive differences are doing better than predicted, while those with negative differences are doing worse
Make a table with the city name and the difference, ordered from best to worst by the size of the difference. (In the following section, we will learn more about how to use these differences, which we call "residuals.")