The interaction between trend and seasonality
نویسنده
چکیده
X-12-ARIMA makes some assumptions about the relationship between trend and seasonality that are not always understood by users. In its simplest form, the observed series Yt can be considered a combination of three components: the trend-cycle Ct, the seasonal component St, and the irregular or random component It. Each of these components can enter the equation by multiplication or addition. Thus we have eight possible models:
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