The Willow River Mining Company mines and ships coal. It has experienced the following demand for coal during the past eight years:
Year Coat Sales (tons)
1 ...........4260
2 ...........4510
3 ...........4050
4 ...........3720
5 ...........3900
6 ...........3470
7 ...........2890
8 ............3100
Develop an adjusted exponential smoothing model (α = 0.30, β = 0.20) and a linear trend line model, and compare the forecast accuracy of the two using MAD. Indicate which forecast seems to be most accurate.