I have a question regarding forecasting with my ARIMA model. Let's say we have found ARIMA(1,1,1) as the best model based on AIC or BIC.
Now, if I want to estimate the value of (t+1) I can substitute in the equation the values of y(0) and e(0). Ok, so I would like to predice now for the horizon t=2. What can I do with the value of e(1) if it is in the future, thus, I don't know the real value and I cannot calculate the error!?
I would say there must be a way to also estimate the error (based on expectancies) or make future errors 0, but then my MA part is completely useless right?