The forecast error is the difference between the actual value and the forecast value for the corresponding period.
where E is the forecast error at period t, Y is the actual value at period t, and F is the forecast for period t.
Measures of aggregate error:
Mean Absolute Error (MAE)
Mean Absolute Percentage Error (MAPE)
Percent Mean Absolute Deviation (PMAD)
Mean Squared Error (MSE)
Root Mean Squared Error (RMSE)
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