A manufacturer of snow chain is considering building a new production plant to cope with growing demand. A tyre firm is interested in investing in the company and has been provided with the following quarterly sales figures:
Unit Sales: 1997-2000 (000s)
| Year | Q1 | Q2 | Q3 | Q4 |
| 1 |
441.1 |
397.7 |
396.1 |
472.8 |
| 2 |
476.4 |
454.4 |
450.8 |
553.5 |
| 3 |
580.7 |
573.2 |
571.6 |
703.6 |
| 4 |
692.0 |
676.5 |
659.9 |
752.8 |
1) Calculate the trend line using the moving average method.
2) Estimate and then eliminate the season variation component. In other words find the deseasonalised data.