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First Column Period | Second Column Sales(Y)

1	30
2	34
3	38
4	42
5	36
6	40
7	48
8	44
9	46
10	52
11	48
12	60
13	62
14	61
15	58
16	66
17	70
18	72
19	76
20	68
21	78
22	82
23	92
24	86

1. Run 3-periods and 4-periods moving average forecasts for the above sales data and compare the forecasts using MAD, MAPE, MSE, RMSE. Forecast for one period ahead (beyond the sample). Also calculate the Mean Percentage Error (MPE) for MA(3) and MA(4) forecasts and discuss the systematic bias (if any) illustrating with the plot of actual vs forecasted values for both MA(3) and MA(4) forecasts. Why did such a systematic bias occur? Correct this bias by performing a Double Moving Average method with four periods and plot the errors of DMA(4). Calculate its MAD, MAPE, MSE, RMSE, and MPE and compare with simple MA(4) forecast. Make a forecast for period 25 (one period beyond the sample) using DMA(4).