which internal regressors can be used to predict seasonality? what is the function of the external regressors does auto.arima work yearly seasonality? does auto.arima automatically calculate does sas regressor calculate r is arima correct what is auto.arima used for can you use external regressors in r does arima calculate ma can we use sas external regressors can sas calculate seasonality auto.arima r calculates what can the sas r regressor r make correct seasonal estimates what is the function of a regressor in sas which of the following would be used in auto.arima can an external regressor make the correct forecast how does arima calculate seasonality how does auto.arima calculate the optimal MA how to calculate seasonality arima can arima be used for seasonality