Construct a table similar to Table P-14 with the natural logarithms of monthly sales. For example, the value for January 2000 is ln(154) = 5.037.
Table P-14
a. Perform an additive decomposition of ln(sales), assuming the model
Y = T + S + I.
b. Would you use the trend component, the seasonal component, or both to forecast?
c. Provide forecasts of ln(sales) for the remaining months of 2006.
d. Take the antilogs of the forecasts calculated in part c to get forecasts of the actual sales for the remainder of 2006.
e. Compare the forecasts in part d with those in Problem 14, part c. Which set of forecasts do you prefer? Why? |

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