<s>
In	O
the	O
classical	O
regression	O
setting	O
,	O
the	O
closeness	O
of	O
to	O
is	O
measured	O
via	O
the	O
risk	O
,	O
also	O
called	O
the	O
mean	B-Algorithm
squared	I-Algorithm
error	I-Algorithm
(	O
MSE	O
)	O
.	O
</s>
<s>
From	O
a	O
practical	O
point	O
of	O
view	O
,	O
the	O
use	O
of	O
the	O
MAPE	O
as	O
a	O
quality	O
function	O
for	O
regression	O
model	O
is	O
equivalent	O
to	O
doing	O
weighted	O
mean	B-General_Concept
absolute	I-General_Concept
error	I-General_Concept
(	O
MAE	O
)	O
regression	O
,	O
also	O
known	O
as	O
quantile	O
regression	O
.	O
</s>
<s>
The	O
use	O
of	O
the	O
MAPE	O
as	O
a	O
loss	O
function	O
for	O
regression	O
analysis	O
is	O
feasible	O
both	O
on	O
a	O
practical	O
point	O
of	O
view	O
and	O
on	O
a	O
theoretical	O
one	O
,	O
since	O
the	O
existence	O
of	O
an	O
optimal	O
model	O
and	O
the	O
consistency	O
of	O
the	O
empirical	B-General_Concept
risk	I-General_Concept
minimization	I-General_Concept
can	O
be	O
proved	O
.	O
</s>
<s>
WMAPE	B-General_Concept
(	O
sometimes	O
spelled	O
wMAPE	B-General_Concept
)	O
stands	O
for	O
weighted	O
mean	O
absolute	O
percentage	O
error	O
.	O
</s>
<s>
Confusingly	O
,	O
sometimes	O
when	O
people	O
refer	O
to	O
wMAPE	B-General_Concept
they	O
are	O
talking	O
about	O
a	O
different	O
model	O
in	O
which	O
the	O
numerator	O
and	O
denominator	O
of	O
the	O
wMAPE	B-General_Concept
formula	O
above	O
are	O
weighted	O
again	O
by	O
another	O
set	O
of	O
custom	O
weights	O
.	O
</s>
