Question
Suppose these data show the number of gallons of gasoline sold by a gasoline distributor in Bennington, Vermont, over the past 12 weeks. Week Sales
Suppose these data show the number of gallons of gasoline sold by a gasoline distributor in Bennington, Vermont, over the past 12 weeks.
Week | Sales (1,000s of gallons) |
---|---|
1 | 15 |
2 | 19 |
3 | 17 |
4 | 21 |
5 | 16 |
6 | 14 |
7 | 21 |
8 | 19 |
9 | 23 |
10 | 21 |
11 | 16 |
12 | 23 |
(a)Using a weight of
1 |
2 |
for the most recent observation,
1 |
3 |
for the second most recent observation, and
1 |
6 |
for third most recent observation, compute a three-week weighted moving average for the time series. (Round your answers to two decimal places.)
Week | Time Series Value | Weighted Moving Average Forecast |
---|---|---|
1 | 15 | |
2 | 19 | |
3 | 17 | |
4 | 21 | |
5 | 16 | |
6 | 14 | |
7 | 21 | |
8 | 19 | |
9 | 23 | |
10 | 21 | |
11 | 16 | |
12 | 23 |
(b)Compute the MSE for the weighted moving average in part (a). (Round your answer to two decimal places.)MSE =
Do you prefer this weighted moving average to the unweighted moving average?
The MSE for the unweighted moving average is 13.33.
The weighted moving average is preferred because it has a smaller MSE compared to the unweighted moving average.
The weighted moving average is preferred because it has a larger MSE compared to the unweighted moving average.
The unweighted moving average is preferred because it has a smaller MSE compared to the weighted moving average.
The unweighted moving average is preferred because it has a larger MSE compared to the weighted moving average.
(c)Suppose you are allowed to choose any weights as long as they sum to 1. Could you always find a set of weights that would make the MSE at least as small for a weighted moving average than for an unweighted moving average? Why or why not?
No, an unweighted moving average always has a smaller MSE than a weighted moving average.
Yes, because an unweighted moving average is just a weighted moving average where the weights are equal.
Yes, a weighted moving average always has a smaller MSE than an unweighted moving average.
No, sometimes you need to let the weights sum to a number higher/lower than 1 in order to get a smaller MSE than the one for an unweighted moving average.
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