Hi,
When I use "Match" to generate the matched pairs and estimate ATT, the ATT
value is different each time I run "Match" anew although the number of
successful matches remains the same.
Secondly, it is still unclear to me how Match estimates ATT to begin with.
It doesn't say in the help file how $est is arrived at.
Thanks you!
Andy
match.out <- Match(Y=y, Tr=Tr, X=pscore,
estimand="ATT", M=1,
BiasAdjust=F, replace=F, sample=T)
summary(match.out)
Estimate... 293.31
SE......... 7.9789
T-stat..... 36.760
p.val...... < 2.22e-16
Original number of observations.............. 1000 Original number of
treated obs............... 255 Matched number of
observations............... 255 Matched number of observations
(unweighted). 255
match.out <- Match(Y=y, Tr=Tr, X=pscore,
estimand="ATT", M=1,
BiasAdjust=F, replace=F, sample=T)
summary(match.out)
Estimate... 296.92
SE......... 7.9923
T-stat..... 37.15
p.val...... < 2.22e-16
Original number of observations.............. 1000 Original number of
treated obs............... 255 Matched number of
observations............... 255 Matched number of observations
(unweighted). 255