Can you please tell me what should be the values of ACF and PACF from the graphs I have attached? I think it should be ($p=0$, $d=1$, $q=3$). I have differenced the data once so $d=1$ and there are three spikes in ACF so $q=3$. But function auto.arima
from "forecast" package in R is giving the answer as (0,0,1).
Also, what should be the values for the seasonal $P$, $D$, $Q$ and its period value?
Best Answer
Firstly, inferring from the ACF and PACF plots of the data, I would say your series is already stationary. There is no need for first order differencing.
Please refer to the following link for a better understanding on selecting the degree of differencing and order of AR and MA for ARIMA models.
https://people.duke.edu/~rnau/411arim3.htm