The following quarterly data show the demand for the most recent four years for a product. Develop a forecast for quarters 17 through 20 using the classical decomposition of a time series.
Period at
1…………………………1566
2…………………………670
3…………………………1810
4…………………………434
5…………………………1448
6…………………………668
7…………………………1741
8…………………………391
9…………………………1127
10…………………………533
11…………………………1332
12…………………………340
13…………………………830
14…………………………389
15…………………………945
16…………………………220