The fi le P02_28.xlsx contains total monthly U.S. retail sales data for a number of years. There are really two series, one of actual sales and one of seasonallyadjusted sales. The latter adjusts for any possible season-ality, such as higher sales in December and lower sales in February, so that any trends are more apparent.

a. Create a graph of both time series and comment on any observable trends, including a possible seasonal pattern, in the data. Does seasonal adjustment make a difference? How?

b. Based on your time series graph of actual sales, make a qualitative projection about the total retail sales levels for the next 12 months. Specifically, in which months of the subsequent year do you expect retail sales levels to be highest? In which months of the subsequent year do you expect retail sales levels to be lowest?