<s>
TWANG	B-Algorithm
,	O
the	O
Toolkit	O
for	O
Weighting	O
and	O
Analysis	O
of	O
Nonequivalent	O
Groups	O
,	O
developed	O
by	O
the	O
statistics	O
group	O
of	O
the	O
RAND	O
Corporation	O
,	O
contains	O
a	O
set	O
of	O
functions	O
to	O
support	O
Rubin	O
causal	O
modeling	O
of	O
observational	O
data	O
through	O
the	O
estimation	O
and	O
evaluation	O
of	O
propensity	O
score	O
weights	O
by	O
applying	O
gradient	B-Algorithm
boosting	I-Algorithm
.	O
</s>
