a) 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.