https://communities.sas.com/t5/SAS-Forecasting-and-Econometrics/Forecast-Studio-Differencing-for-a-manually-added-event/m-p/535017#M3443 <P>Hello,</P><P>&nbsp;</P><P>I have a Forecast Studio project with a weekly time scale and thus the seasonal cycle length is 52. I've noticed that when I add an event to a copy of an automatically generated Subset ARIMA model that has DIF = (1 52), the event is then assigned DIF = (53). All of the other events that have been automatically included in the model have the same differencing as the model, i.e. DIF = (1 52). To the best of my knowledge, an event's differencing should be the same as the model's differencing. Is there an explanation as to why it assigns DIF = (53) instead of (1 52)?</P><P>&nbsp;</P><P>Thanks,</P><P>Blake</P> Tue, 12 Feb 2019 21:13:59 GMT blakeoft 2019-02-12T21:13:59Z https://communities.sas.com/t5/SAS-Forecasting-and-Econometrics/Forecast-Studio-Differencing-for-a-manually-added-event/m-p/535017#M3443 <P>Hello,</P><P>&nbsp;</P><P>I have a Forecast Studio project with a weekly time scale and thus the seasonal cycle length is 52. I've noticed that when I add an event to a copy of an automatically generated Subset ARIMA model that has DIF = (1 52), the event is then assigned DIF = (53). All of the other events that have been automatically included in the model have the same differencing as the model, i.e. DIF = (1 52). To the best of my knowledge, an event's differencing should be the same as the model's differencing. Is there an explanation as to why it assigns DIF = (53) instead of (1 52)?</P><P>&nbsp;</P><P>Thanks,</P><P>Blake</P> Tue, 12 Feb 2019 21:13:59 GMT https://communities.sas.com/t5/SAS-Forecasting-and-Econometrics/Forecast-Studio-Differencing-for-a-manually-added-event/m-p/535017#M3443 blakeoft 2019-02-12T21:13:59Z