The spreadsheet provides data for the past 30 weeks of sales for product X. Based on the
Question:
The spreadsheet provides data for the past 30 weeks of sales for product X. Based on the data, do the following questions.
(a) Plot the data. Just by looking at the plot, do you think a 3-week simple moving average would be a better forecast, or a 6-week simple moving average? Just by looking at the plot, do you think an exponential smoothing with value of α = 0.2 would be a better forecast or would α = 0.6 be better? Explain your reasoning. (Different people could reach different conclusions, but you need to give good reasons for your conclusions.)
(b) Compute the four possible forecasts: 3-week and 6-week simple moving average and exponential smoothing with value of α = 0.2 and α = 0.6. For exponential smoothing, use F1 = 600 (the forecast for week 1) for initialization. Based on your calculation, which one of the above four forecasts is the best? Justify your answer by calculating MAD.
Week | Actual Sales |
1 | 574 |
2 | 1004 |
3 | 717 |
4 | 1076 |
5 | 1076 |
6 | 932 |
7 | 1291 |
8 | 1219 |
9 | 932 |
10 | 1219 |
11 | 1219 |
12 | 1076 |
13 | 1650 |
14 | 1650 |
15 | 1434 |
16 | 1219 |
17 | 1291 |
18 | 1578 |
19 | 1793 |
20 | 1721 |
21 | 1578 |
22 | 1865 |
23 | 1434 |
24 | 1793 |
25 | 1865 |
26 | 1506 |
27 | 1650 |
28 | 1506 |
29 | 1721 |
30 | 1506 |