Skip Section 3.3.3, “Three dimensional scatterplots,” on pages 45-46. The illustration is nice, but it is not tested on the final exam.

Read Section 3.3.4, “Conditioning plots,” on pages 46-47. Know how to interpret the plot in Figure 3.20 on page 48.

Read the summary on pages 47-48.

Conditioning plots (or co-plots) are useful when the relation of the response variable (the Y variable or dependent variable) to the explanatory variable depends on the value of the explanatory variable.

Illustration: You are examining the relation of auto insurance claim frequency to age of the driver. The relation differs for men vs women and for young drivers vs adult drivers. For young men, claim frequency is strongly related to age. For young women and all adult drivers, the relation is weaker. Conditioning plots how the relations visually.