The data file Armstead contains the monthly number of calls received by Armstead & Associates, a company that was formed to help individuals locate long-term health care assistance for elderly individuals.

a. Plot these data in a time-series graph. Based on the graph, what time-series components are in the data?

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.

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.