| Period | Demand | 4 Week Moving Average |
| 1 | 100 | |
| 2 | 150 | |
| 3 | 230 | |
| 4 | 180 | |
| 5 | 300 | 165 |
| 6 | 320 | 215 |
| 7 | 290 | 257.5 |
| 8 | 160 | 272.5 |
| 9 | 180 | 267.5 |
| 10 | 140 | 237.5 |
| 11 | 200 | 192.5 |
| 12 | 210 | 170 |
Table 15: Four-Week Moving Average
Moving averages use a pre-determined number of periods and each time the forecast is re-calculated the oldest data is dropped from the calculation (becoming known then as lagged demand) and the latest data is included.
For example, using the data from Table 15 and in period 4 calculating the forecast using a 4 period moving average for period 5 would be:
(100+150+230+180) / 4 = 165
Doing the same calculation in period 5 to obtain the forecast for period 6 would result in the period 1 demand of 100 becoming lagged (dropped) and the period 5 demand of 300 being included:
(150+230+180+300) / 4 = 215