I have a time series of 61 monthly observations and I would like to build an ARIMA forecasting model. To test my model, I separated my data into a training set of the 51 first observations, and a test set with the remaining 10.
Now my question is, when I am plotting the
PACF to get an idea of the appropriate
q parameters I should use in my model, should I plot the
PACF only on my training set? Knowing that my ARIMA will be applied on the training set to forecast 10 future values, that I will compare to the observed ones in my test set.