이처럼 Decrease Dummy를 포함하게 되면 NETINC의 기울기 차이(α4)뿐 아니라 y절편 차이(α3)를 동시에 검증한다.
In this way, when the Decrease Dummy is included, not only the difference in slope of NETINC (α4) but also the difference in y-intercept (α3) are simultaneously verified.