Suppose we measure the height and weight of a collection of people. We could make a plot of the results, using an asterisk for each person. The horizontal position is determined by the person’s height, and the vertical position is determined by the person’s weight. The resulting plot might look something like that shown in Figure 4-1.
Not surprisingly, these two measurements are highly correlated; tall people tend to weigh more than short people. Of course, the correlation is not perfect; some people are built differently from others.
One thing that jumps out of a plot of ...
