Excel Forecast

Using the data from Problem 3.1 (page 128) on your book develop three forecasts for 2015 January. 

1) A 12-month moving average

2) Exponential smoothing with alpha that corresponds to a 12 month moving average block (see formula 3.26). Initialize by averaging the first 11 months. 

3) Winter's method using Centered MA12 (then you need MA2 because the center of 12 is 6.5). Get alphaHW, betaHW from formulas 3.34 and 3.35, respectively and gammaHW is 0.15.

Calculate MAD for each method.