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Chapter 11

Using the model

4.1 Forecasting

 Typically ignore cyclical and random elements

 Additive: Y = T + S

 Multiplicative: Y = T × S

4.2 'De-seasonalising' data

 Effectively the same as extracting the trend

 Typically ignore cyclical and random elements

 Additive: T = Y – S

 Multiplicative: T = Y ÷ S

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