EXAMPLE 6 Scatterplots and Correlation
The scatterplots in Figure 6.9 all involve the same scale for the horizontal and vertical axes and the same standard deviation value for the - and -variables. From these scatterplots, we are able to see how values of closer to 1 or −1 correspond to stronger straight-line relationships.
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Figure 6.9: Figure 6.9 How the correlation measures the direction and strength of straight-line association.