The quarterly sales data (number of copies sold) for a collegetextbook over the past three years follow.
Click on the datafile logo to reference the data.
quarter year 1 year 2 year 3Â Â
1 1690 1800 1850
2 940 900 1100
3 2625 2900 2930
4 2500 Â Â 2360 Â Â 2615
e. Deseasonalize the time series (to 3decimals).
| Year | Quarter | Deseasonalized Value |
| 1 | 1 | |
| 2 | |
| 3 | |
| 4 | |
| 2 | 1 | |
| 2 | |
| 3 | |
| 4 | |
| 3 | 1 | |
| 2 | |
| 3 | |
| 4 | |
f. Compute the linear trend equation for thedeseasonalized data (to 1 decimal if necessary).
Deseasonalized Value =____ +____ Period
Compute the forecast sales using the linear trend equation (to 1decimal).
| Forecast for quarter 1 | |
| Forecast for quarter 2 | |
| Forecast for quarter 3 | |
| Forecast for quarter 4 | |
g. Adjust the linear trend forecasts using theadjusted seasonal indexes computed in part (c) (tothe nearest whole number).
| Forecast for quarter 1 | |
| Forecast for quarter 2 | |
| Forecast for quarter 3 | |
| Forecast for quarter 4 | |
