Hello,
I am working with Propensity Score Matching and came across the
following problems (code below).
1) When comparing the results from psmatch2 with pscore (and
subsequently att*), I only get the same results if I do not use the
common support options. If I do that, the results differ. I guess the
common support is selected differently with the two commands, but I
could not find more information. Can somebody explain the difference?
2) When I use psmatch2 again with the common support option, I get
different results for ATT depending on if I also use the ATE option or
not. As I understood the help file, the ATE option should only add
further details in the output instead of changing the calculation,
therefore I do not understand the changing result.
Thanks for your time and consideration,
Sarah
psmatch2 emsbinary logvossd, radius cal(0.1) out(perfbinary) logit com ate
Variable Sample | Treated Controls Difference S.E. T-stat
----------------------------+-----------------------------------------------------------
perfbinary Unmatched | .625 .582417582 .042582418
.045186234 0.94
ATT | .612903226 .620169943 -.007266717
.048401842 -0.15
ATU | .581497797 .55933642 -.022161378
ATE | -.018370454
psmatch2 emsbinary logvossd, radius cal(0.1) out(perfbinary) logit com
Variable Sample | Treated Controls Difference S.E. T-stat
----------------------------+-----------------------------------------------------------
perfbinary Unmatched | .625 .582417582 .042582418
.045186234 0.94
ATT | .612903226 .620364171 -.007460945
.048395422 -0.15
attr perfbinary emsbinary logvossd, pscore(pscore) logit comsup
n. treat. n. contr. ATT Std. Err. t
---------------------------------------------------------
159 454 0.027 0.046 0.580
--
Sarah Wichmann
Eichelhäherkamp 94b
22397 Hamburg
Handy: 0046 73 683 57 91
0049 173 612 44 42
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