I have a question about the role of the MAPE in the ARIMA model optimization.
For a daily time series I have found that the best model (using the Box-Jenkins approach) is an ARIMA(7,0,7)(0,0,0). If I check the ACF and PACF of the model residuals, I see that there is no more information I can extract; see the right panel of the picture below.
However, the MAPE value is as high as 18209.16. To me this sounds too high according to its definition.
Have I missed something? Can I accept this ARIMA model even if it has such a high MAPE?
By the way, I am getting similar results if I use
auto.arima; MAPE is always big.