13.35 Nonlinear effects of age Suppose you fit a straight-line regression model to y = number of hours worked (excluding time spent on household chores) and x = age of the subject. Values of y in the sample tend to be quite large for young adults and for elderly people, and they tend to be lower for other people. Sketch what you would expect to observe for

(a) the scatterplot of x and y and

(b) a plot of the residuals against the values of age.