<s>
A	O
decision	B-Algorithm
stump	I-Algorithm
is	O
a	O
machine	O
learning	O
model	O
consisting	O
of	O
a	O
one-level	O
decision	B-Algorithm
tree	I-Algorithm
.	O
</s>
<s>
That	O
is	O
,	O
it	O
is	O
a	O
decision	B-Algorithm
tree	I-Algorithm
with	O
one	O
internal	O
node	O
(	O
the	O
root	O
)	O
which	O
is	O
immediately	O
connected	O
to	O
the	O
terminal	O
nodes	O
(	O
its	O
leaves	O
)	O
.	O
</s>
<s>
A	O
decision	B-Algorithm
stump	I-Algorithm
makes	O
a	O
prediction	O
based	O
on	O
the	O
value	O
of	O
just	O
a	O
single	O
input	O
feature	B-Algorithm
.	O
</s>
<s>
Sometimes	O
they	O
are	O
also	O
called	O
1-rules	B-Algorithm
.	O
</s>
<s>
Depending	O
on	O
the	O
type	O
of	O
the	O
input	O
feature	B-Algorithm
,	O
several	O
variations	O
are	O
possible	O
.	O
</s>
<s>
For	O
nominal	O
features	O
,	O
one	O
may	O
build	O
a	O
stump	O
which	O
contains	O
a	O
leaf	O
for	O
each	O
possible	O
feature	B-Algorithm
value	O
or	O
a	O
stump	O
with	O
the	O
two	O
leaves	O
,	O
one	O
of	O
which	O
corresponds	O
to	O
some	O
chosen	O
category	O
,	O
and	O
the	O
other	O
leaf	O
to	O
all	O
the	O
other	O
categories	O
.	O
</s>
<s>
For	O
continuous	O
features	O
,	O
usually	O
,	O
some	O
threshold	O
feature	B-Algorithm
value	O
is	O
selected	O
,	O
and	O
the	O
stump	O
contains	O
two	O
leaves	O
—	O
for	O
values	O
below	O
and	O
above	O
the	O
threshold	O
.	O
</s>
<s>
Decision	B-Algorithm
stumps	I-Algorithm
are	O
often	O
used	O
as	O
components	O
(	O
called	O
"	O
weak	B-Algorithm
learners	I-Algorithm
"	O
or	O
"	O
base	O
learners	O
"	O
)	O
in	O
machine	B-Algorithm
learning	I-Algorithm
ensemble	I-Algorithm
techniques	O
such	O
as	O
bagging	B-Algorithm
and	O
boosting	B-Algorithm
.	O
</s>
<s>
For	O
example	O
,	O
a	O
Viola	B-General_Concept
–	I-General_Concept
Jones	I-General_Concept
face	O
detection	O
algorithm	O
employs	O
AdaBoost	B-Algorithm
with	O
decision	B-Algorithm
stumps	I-Algorithm
as	O
weak	B-Algorithm
learners	I-Algorithm
.	O
</s>
<s>
The	O
term	O
"	O
decision	B-Algorithm
stump	I-Algorithm
"	O
was	O
coined	O
in	O
a	O
1992	O
ICML	B-General_Concept
paper	O
by	O
Wayne	O
Iba	O
and	O
Pat	O
Langley	O
.	O
</s>
