. Consider the cascade process data in Table 10-5. In fitting regression models to both y, and y2 you will find that not all of the process variables are required"

to obtain a satisfactory regression model for the output variables. Remove the nonsignificant variables from these equations and obtain subset regression models for both y, and y2. Then con-
struct individuals control charts for both sets of residuals. Compare them to the residual control charts in the text (Fig.
10-11) and from Exercise 10-18. Arc there any substantial differences between the charts from the two differ-
ent approaches to fitting the regression models?