This study developed a hybrid model that combined the SARIMA
model (linear approach) and the ANN model (non-linear approach).
First, the predicted value ðbL
tÞ can be calculated, as well as the
predicted error ðest
Þ against the observed value (Zt) by using the SARIMA model (refer to equation (10)). Here, the predicted error
ðest
Þ should satisfy independence and homoscedasticity [59].