For instance, I have an ARIMA (1,0,1) process (determined by auto.arima function, and analysis of residuals which are white noise). I know how to read an ACF for a strict AR(p) process or a MA(q) process, but how does one infer from the ACF and PACF that we have an ARIMA (p,q) process. Are there any resources out there that can help me with this?
E.g. For my ARIMA (1,0,1) process mentioned above, here is what my ACF and PACF look like:
How are these characteristic of a ARIMA(1,0,1) process?
Again, this ACF and PACF are not characteristic of your sole AR(p) or MA(q) process. It's seems "random". Can you tell me how this is supposed to lead me to determining an ARIMA model (in this case, probably an ARIMA(1,0,2) process ) ?