The numerator can be written either as ∣Forecast i −Actual i ∣ or ∣ Actual i −Forecast i ∣. This difference doesn't change the outcome because the absolute value operation makes the order of subtraction irrelevant. So whether you see "Forecast - Actual" or "Actual - Forecast," the result remains the same due to the absolute value, and both versions are correct.
The formulas for SMAPE change - On some slides it shows Forecast - Actual on the numerator for SMAPE and on another it is Actual - Forecast.
The numerator can be written either as ∣Forecast i −Actual i ∣ or ∣ Actual i −Forecast i ∣. This difference doesn't change the outcome because the absolute value operation makes the order of subtraction irrelevant.
So whether you see "Forecast - Actual" or "Actual - Forecast," the result remains the same due to the absolute value, and both versions are correct.