Problem 15-08 (Algorithmic) Refer again to the gasoline sales time series data i
ID: 375241 • Letter: P
Question
Problem 15-08 (Algorithmic)
Refer again to the gasoline sales time series data in the following table.
Using a weight of 1/2 for the most recent observation, 1/3 for the second most recent, and 1/6 for third most recent, compute a three-week weighted moving average for the time series. Use rounded for two decimal places values for intermediate colculations.
Compute the MSE for the weighted moving average in part a. Do you prefer this weighted moving average to the unweighted moving average? Remember that the MSE for the unweighted moving average is 10.22. Round your answer to two decimal places.
MSE =
Explanation / Answer
MSE = SUM of Error Square/(Total Error values -1)
Forecast for week 4 = 1/2*20 + 1/3*34 + 1/6*18 = 21
MSE = (9+7.11+53.78+.....+23.36)/(9-1) = 23.54
No, I will prefer unweighted moving average as MSE is lower
Week Sales Forecast (F) Error (D-F) Error Sq 1 18 2 24 3 20 4 24 21.00 3.00 9.00 5 20 22.67 (2.67) 7.11 6 14 21.33 (7.33) 53.78 7 20 17.67 2.33 5.44 8 17 18.00 (1.00) 1.00 9 25 17.50 7.50 56.25 10 21 21.50 (0.50) 0.25 11 16 21.67 (5.67) 32.11 12 24 19.17 4.83 23.36