Question 11.77

11.77 Differences in slopes and intercepts.

Refer to the previous exercise. Verify that the coefficient of is equal to the slope for Group B minus the slope for Group A in each of these cases. Also, verify that the coefficient of is equal to the intercept for Group B minus the intercept for Group A in each of these cases. Do you think these two results will be true in general? Explain your answer.

11.77

(a) , which is the coefficient of , which is the coefficient of . (b) , which is the coefficient of , which is the coefficient of . (c) , which is the coefficient of , which is the coefficient of . These results will be true in general as long as is an indicator variable with values 0 and 1.