WMAPE

WMAPE (sometimes spelled wMAPE) stands for Weighted Mean Absolute Percentage Error.[1] It is a measure of prediction accuracy of a forecasting method. It's a variant of MAPE in which errors are weighted by sales volume[1].

Its formula is[2]:

${\displaystyle {\mbox{WMAPE}}={\frac {\sum _{t=1}^{n}\left|A_{t}-F_{t}\right|}{\sum _{t=1}^{n}\left|A_{t}\right|}}}$

The advantage of this metric over MAPE is that this overcomes the 'infinite error' issue[2].

References

1. "WMAPE: Weighted Mean Absolute Percentage Error".
2. "Statistical Forecast Errors".