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ML Academy

Introduced on day 16

WAPE (weighted absolute percentage error)

Total absolute error divided by total actual volume, times 100; a volume-weighted ratio of sums that stays defined unless every actual is zero.

In detail

WAPE = 100 x sum|y - yhat| / sum|y|. It answers "what share of the volume was misforecast" and ties directly to error x volume x unit cost. It is a practitioner measure (also seen as WMAPE), not one of the measures proposed in Hyndman and Koehler (2006). Compute it at the level where actuals cannot sum to zero.