Weighted Absolute Percentage Error (WAPE) 

The weighted absolute percentage error (WAPE) is defined in an update rule and is calculated per data source.

The system uses the following algorithm for this:

 

                t-1                         t-1

WAPE (t, s,n) = Σ ( APE(i,i-s) * Act(i) ) / Σ Act(i)

                i=t-n                       i=t-n                                                                            

 

Explanation of Symbols

Symbol	Description
t	Current calendar week
s	Shift into the future for which the WAPE is to be calculated
n	Number of calendar weeks to be taken into account in the calculation
APE(i, i-s)	WAPE for calendar week i and period i-s
Act(i)	Actual sales quantity for calendar week i

By definition there is no WAPE value for the current calendar week.