13.28. A regression model is fitted to annual income

(thousands of dollars), using predictors age and marital status. Table 13.20 shows the sample mean incomes and the adjusted means for the model.

How could the adjusted means be so different from the unadjusted means? Draw a sketch to help explain.

TABLE 13.20 Mean Mean Adjusted Mean Group Age Income Income Married 44 40 30 Divorced 35 30 30 Single 26 20 30 In Exercises 13.29-13.30, select the correct response(s).