The quarterly sales data (number of copies sold) for a college textbook over the past three years follow
Quarter Year 1 Year 2 Year 3
1 1690 1800 1850
2 940 900 1100
3 2625 2900 2930
4 2500 2360 2615
Construct a time series plot. What type of pattern exists in the data?
Use the following dummy variables to develop an estimated regression equation to
account for any seasonal effects in the data: Qtr1 1 if Quarter 1, 0 otherwise;
Qtr2 1 if Quarter 2, 0 otherwise; Qtr3 1 if Quarter 3, 0 otherwise.
Compute the quarterly forecasts for next year.
Let t 1 to refer to the observation in quarter 1 of year 1; t 2 to refer to the o