Chapter 8, Problem 11E

(a)

To determine

To explain what each of the residual plots below indicates about the appropriateness of the linear model that was fit to the data.

Explanation of Solution

In the part (a) residual plot it can be seen that the points in the residual plot does not show any pattern that is neither upward nor downward. We cannot say about what kind of relationship the plot is showing. Thus, we can say that this model shown in the residual plot of part (a) is appropriate and show some linearity in it.

(b)

To determine

To explain what each of the residual plots below indicates about the appropriateness of the linear model that was fit to the data.

Explanation of Solution

In the residual plot shown in part (b), we can say that the points in the residual plot is showing an upward direction and then they are showing an downward direction. Thus, the relationship between the points keeps changing as we move ahead. Thus, we can say that the model predicted by the residual plot of part (b) is not appropriate and the relationship shown in the plot in non-linear.

(c)

To determine

To explain what each of the residual plots below indicates about the appropriateness of the linear model that was fit to the data.

Explanation of Solution

In the residual plot of part (c), we can say that the points in the residual plot shows the constant direction and then as we move ahead the points are spread out in an uneven direction. Thus, the spread is changing in the points. So, we can say that the model predicted by the residual plot in part (c) is not appropriate model.