Managerial Economics 12th Edition by Christopher Thomas,Charles Maurice

تمرين 3

Rubax, a U.S. manufacturer of athletic shoes, estimates the following linear trend model for shoe sales:
Q t = a + bt + c 1 D 1 + c 2 D 2 + c 3 D 3
where
Q t = sales of athletic shoes in the t th quarter
t = 1, 2,.... , 28 [2007(I), 2007(II),.... , 2013(IV)]
D 1 = 1 if t is quarter I (winter); 0 otherwise
D 2 = 1 if t is quarter II (spring); 0 otherwise
D 3 = 1 if t is quarter III (summer); 0 otherwise
The regression analysis produces the following results:

a. Is there sufficient statistical evidence of an upward trend in shoe sales?
b. Do these data indicate a statistically significant seasonal pattern of sales for Rubax shoes? If so, what is the seasonal pattern exhibited by the data?
c. Using the estimated forecast equation, forecast sales of Rubax shoes for 2014(III) and 2015(II).
d. How might you improve this forecast equation?