Weighted Moving Averages

Week	Sales
1	39
2	44
3	40
4	45
5	38
6	43
7	39
8

Example 1

Forcast sales using 4-week weighted moving averages with weights 0.4, 0.3, 0.2, 0.1

Week	Sales	4WMA	|Error|
1	39
2	44
3	40
4	45
5	38	42.7	4.7
6	43	41.1	1.9
7	39	41.6	2.6
8		40.6	MAD
			3.07

F₅ = 0.4*45+0.3*40+0.2*44+0.1*39=42.7

F₆=0.4*38+0.3*45+0.2*40+0.1*44=41.1

F₇=0.4*43+0.3*38+0.2*45+0.1*40=41.6

F₈=0.4*39+0.3*43+0.2*38+0.1*45=40.6

Example 2

Forcast sales using 2-week weighted moving averages with weights 0.6, 0.4

Week	Sales	2WMA	|Error|
1	39
2	44
3	40	42.0	2.0
4	45	41.6	3.4
5	38	43.0	5.0
6	43	40.8	2.2
7	39	41.0	2.0
			MAD
			2.92

F₃=0.6 * 44 + 0.4 * 39 = 42.0

F₄=0.6 * 40 + 0.4 * 44 = 41.6

F₅=0.6 * 45 + 0.4 * 40 = 43.0

F₆=0.6 * 38 + 0.4 * 45 = 40.8

F₇=0.6 * 43 + 0.4 * 38 = 41.0

F₈=0.6 * 39 + 0.4 * 43 = 40.6