Answers:

1)

Model	Period 31 Forecast
Naive	29
4-period Moving Average	26
3-period Weighted Moving Average	27.33
Exponential Smoothing (alpha = 0.1)	24.84
Exponential Smoothing (alpha = 0.5)	27.5
Linear Trend	31.14

2)  Choose the linear trend model.  It has the lowest MAD of 2.01.

3)  Choose the naive model.  It has the lowest MSE of 6.34.

4)  The model is out of control.  Although only one instance is required as a cause for inspection, 8 of the 10 errors fall outside the control limits.  It is necessary to either recalibrate the model, or to develop a new model altogether.

 Click on the image to the left to download an Excel spreadsheet of the models described.

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