General Motors (GM) is one of the world€™s largest car and truck manufacturer and employs over 200,000 employees worldwide. In 1970, GM had captured nearly 60% of the U. S. market share. However, due to increased global competition over the past 40 years, GM€™s market share has eroded to less than 18% in 2012. The following data show GM€™s U. S. market share from 2004 until 2012. These data can also be found in the Excel file GM market share.xlsx.

a. Forecast the U. S. market share for GM in 2013 using two period weighted moving average with weights 3 and 1.
b. Calculate the MAD for the forecast in part a.
c. Forecast the U. S. market share for GM in 2013 using exponential smoothing with α = 0.7.
d. Calculate the MAD for the forecast in part c.
e. Which forecast do you have most confidence in? Why?

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Market Share Market Share Year 2004 2005 2006 2007 2008 26.2 33.0 27.3 22.1 22.1 Year 2009 2010 2011 2012 19.7 18.8 19.4 17.9