Problem
Two independent methods of forecasting based on judgment and experience have been prepared each month for the past 10 months. The forecasts and actual sales are as follows:
| Month |
Sales |
Forecast 1 |
Forecast 2 |
| 1 |
835 |
785 |
780 |
| 2 |
835 |
810 |
795 |
| 3 |
825 |
825 |
850 |
| 4 |
835 |
800 |
835 |
| 5 |
790 |
820 |
805 |
| 6 |
840 |
805 |
791 |
| 7 |
800 |
775 |
790 |
| 8 |
850 |
780 |
850 |
| 9 |
815 |
785 |
810 |
| 10 |
785 |
790 |
855 |
|
a. Compute the MSE and MAD for each forecast. (Round your answers to 2 decimal places.)
MSE MAD
Forecast 1
Forecast 2
b. Compute MAPE for each forecast. (Round your intermediate calculations to 5 decimal places and final answers to 4 decimal places.)
MAPE F1 %
MAPE F2 %
c. Prepare a naive forecast for periods 2 through 11 using the given sales data. Compute each of the following; (1) MSE, (2) MAD, (3) tracking signal at month 10, and (4) 2s control limits. (Round your answers to 2 decimal places.)
MSE
MAD
Tracking signal
Control limits 0 ±