For a multiplicative time series model, the sum of the seasonal indexes should equal the number of seasons.

Question

Quizplus · Accepted Answer

In a multiplicative time series model, the seasonal indexes represent the average deviation from the trend for each season. Since these deviations multiply with the trend to produce the seasonal component, their sum should equal the total number of seasons. This property can be used to check the consistency of the seasonal factors estimated by different methods.

For a Multiplicative Time Series Model, the Sum of the Seasonal