DataNet is an Internet service through which clients can
find information and purchase various items such as airline tickets, stereo
equipment, and listed stocks. DataNet has been in operation for four years.
Data on monthly calls for service for the time that the company has been in
business are in the data file called DataNet.
b. Develop the seasonal indexes for each month. Describe
what the seasonal index for August means.
c. Fit a linear trend model to the deseasonalized data for
months 1 through 48 and determine the MAD value. Comment on the adequacy of the
linear trend model based on these measures of forecast error.
d. Provide a seasonally unadjusted forecast using the linear
trend model for each month of the year.
e. Use the seasonal index values computed in part b to
provide seasonal adjusted forecasts for months 49 through 52.