Smoothing Forecast Analysis
Week Widgets Smoothed
No. Sold Forecast 250
1 40 #N/A
2 90 40.00
3 100 75.00 200
4 110 92.50
5 90 104.75 150 Baseline
6 120 94.43
7 109 112.33
8 96 110.00 100 Linear (Baseline)
9 80 100.20
10 120 86.06
11 130 109.82
12 200 123.95
13 190 177.18 0
14 180 186.16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
15 200 181.85 Week
Forecast For Week 16 194.55
The fundamental idea behind smoothing is that each new forecast is obtained in part by moving the prior forecast in a
direction that would have improved the old forecast. The equation is: F[t+1] = F[t] + a x e[t] where:
1. t is the time period
2. F[t] is the forecast at time t, and F[t+1] is the forecast at the time period immediately following time t
3. a is the smoothing constant (Never exceed .7)
4. e[t] is the error: the difference between the forecast for time t and the actual observation at time t
How do you use it? Enter your business units (widgets) and this sheet will forecast unit sales for you.
This sheet is fully functional. To remove protection click Tools / Protection / Unprotect sheet.
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