Hello,
When calculating the MAPE I understand the equation of acutual - forecasted/actual. What i am not fully understanding is how it relates to the ex post forecast. I understand the error total is calculated by using the ex post forecast results based on the system needs for initialization and the number of historical values. What i would like to know is how can i determine the number of historical periods that are aggregated into the MAPE error measurement?
Thank You,
Melissa