Mean percentage error
In statistics, the mean percentage error (MPE) is the computed average of percentage errors by which forecasts of a model differ from actual values of the quantity being forecast. The formula for the mean percentage error is: MPE = 100 % n ∑ t = 1 n f t − a t a t {\displaystyle {\text{MPE}}={\frac {100\%}{n}}\sum _{t=1}^{n}{\frac {f_{t}-a_{t}}{a_{t}}}} where a t {\textstyle a_{t}} is the actual value of the quantity being forecast, f t {\textstyle f_{t}} is the forecast, and n {\textstyle n} is the number of different times for which the variable is forecast.