How an input series enters the model is called its transfer function. Thus, ARIMA models with input series are sometimes referred to as transfer function models. In the preceding regression and ...

Simplify \(\frac{3t + 6}{3t}\). The numerator of this fraction will factorise as there is a common factor of 3. This gives \(\frac{3(t + 2)}{3t}\). Now, there is clearly a common factor of 3 between ...