Sales of tablet computers at Ted Glickman\'s electronics store in Washington, D.
ID: 3040129 • Letter: S
Question
Sales of tablet computers at Ted Glickman's electronics store in Washington, D.C., over the past 10 weeks are shown in the table below:
Week
1
2
3
4
5
6
7
8
9
10
Demand
21
20
29
37
24
29
36
22
26
29
a) The forecast for weeks 2 through 10 using exponential smoothing with = 0.60 and a week 1 initial forecast of 21.0 are (round your responses to two decimal places):
Week
1
2
3
4
5
6
7
8
9
10
Demand
21
20
29
37
24
29
36
22
26
29
Forecast
21.0
b) For the forecast developed using exponential smoothing ( =0.60 and initial forecast 21.0), the MAD = ___sales (round your response to two decimal places).
c) For the forecast developed using exponential smoothing ( =0.60 and initial forecast 21.0), the tracking signal = __(round your response to two decimal places).
Explanation / Answer
Ft+1= 0.6At + (1-0.6)Ft (where Ft = current forecast, Ft+1 = next forecast, At = current sales)
Ft+1= 0.6At + 0.4Ft
Initially At = Ft =21. Solving this for all values from t=1 to t=10, we get
Now,
MAD(Mean absolute deviation) = (sum |et| ) / n where,et = At - Ft
= 52.86/10 = 5.286
Running sum of forecast errors (RSFE) = (sum et) / n
= 11.5/10 = 1.15
Tracking Signal (TS) = RFSE/MAD
= 1.15/5.286
= 0.218
Week sale Forecast 1 21 21 2 20 21 3 29 20.4 4 37 25.56 5 24 32.42 6 29 27.37 7 36 28.35 8 22 32.9 9 26 26.36 10 29 26.14Related Questions
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