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st: RE: Treatment effect not produced when running psmatch2 on STATA 12


From   "Radwin, David" <dradwin@rti.org>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Treatment effect not produced when running psmatch2 on STATA 12
Date   Tue, 2 Jul 2013 19:39:16 -0400

Rekha,

I don't seem to have the same problem using -psmatch2- in Stata 12. Are you showing the entire output? 

The silly example below implies that union membership has a treatment effect on the treated (ATT) of increasing hourly wages by $.89.

Please note that the FAQ asks you to mention authors and locations of user-written programs (-psmatch2- is by Edwin Leuven and Barbara Sianesi and is available from SSC) and not to spell Stata in all capital letters.

David
--
David Radwin
Senior Research Associate
Education Studies Division
RTI International
2150 Shattuck Ave., Suite 800
Berkeley, CA 94704
Phone: 510-665-8274

www.rti.org


. sysuse nlsw88
(NLSW, 1988 extract)

. psmatch2 union age tenure grade south, outcome(wage) logit common

Logistic regression                               Number of obs   =       1866
                                                  LR chi2(4)      =      79.94
                                                  Prob > chi2     =     0.0000
Log likelihood =  -1001.027                       Pseudo R2       =     0.0384

------------------------------------------------------------------------------
       union |      Coef.   Std. Err.      z    P>|z|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
         age |   .0033413    .018228     0.18   0.855    -.0323849    .0390676
      tenure |   .0471613   .0093689     5.03   0.000     .0287986    .0655241
       grade |    .063582   .0221642     2.87   0.004     .0201409    .1070231
       south |  -.6947927   .1166248    -5.96   0.000    -.9233732   -.4662123
       _cons |   -2.16279   .7826216    -2.76   0.006      -3.6967   -.6288799
------------------------------------------------------------------------------
There are observations with identical propensity score values.
The sort order of the data could affect your results.
Make sure that the sort order is random before calling psmatch2.
----------------------------------------------------------------------------------------
        Variable     Sample |    Treated     Controls   Difference         S.E.   T-stat
----------------------------+-----------------------------------------------------------
            wage  Unmatched | 8.68811142   7.22912785   1.45898357    .22164775     6.58
                        ATT | 8.68626376   7.80088291    .88538085   .302022285     2.93
----------------------------+-----------------------------------------------------------
Note: S.E. does not take into account that the propensity score is estimated.

 psmatch2: |   psmatch2: Common
 Treatment |        support
assignment | Off suppo  On suppor |     Total
-----------+----------------------+----------
 Untreated |         0      1,407 |     1,407 
   Treated |         2        457 |       459 
-----------+----------------------+----------
     Total |         2      1,864 |     1,866 



> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
> statalist@hsphsun2.harvard.edu] On Behalf Of Rekha Varghese
> Sent: Tuesday, July 02, 2013 2:28 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: Treatment effect not produced when running psmatch2 on STATA
> 12
> 
> Hi,
> 
> When I used psamtch2 on STATA 12, I get the logit regression to run. But
> the treatment effect is not automatically generated with it. The following
> is the command and output. Is this a STATA 12 issue? Any suggestions on
> how to get the treatment effects to be produced automatically using the
> psmatch2 command? Thanks,
> 
> 
> psmatch2 cctp_treat bdtot admtot vem voth gov_nonfed for_profit rural
> teach_h
> ospital percent_medicare percent_medicaid cmi penalty_3025,
> out(fake_outcome1)
> logit common
> 
> Logistic regression                               Number of obs   =
> 1537
>                                                   LR chi2(12)     =
> 49.23
>                                                   Prob > chi2     =
> 0.0000
> Log likelihood = -902.02616                       Pseudo R2       =
> 0.0266
> 
> --------------------------------------------------------------------------
> ----
>   cctp_treat |      Coef.   Std. Err.      z    P>|z|     [95% Conf.
> Interval]
> -------------+------------------------------------------------------------
> ----
>        bdtot |  -.0003375   .0007795    -0.43   0.665    -.0018653
> .0011903
>       admtot |   .0000136   .0000175     0.78   0.435    -.0000206
> .0000479
>          vem |   1.05e-06   3.02e-06     0.35   0.729    -4.88e-06
> 6.97e-06
>         voth |  -4.83e-08   3.22e-07    -0.15   0.881    -6.78e-07
> 5.82e-07
>   gov_nonfed |   .0583013   .1816423     0.32   0.748    -.2977111
> .4143137
>   for_profit |   -.353263   .1662154    -2.13   0.034    -.6790392   -
> .0274868
>        rural |  -.5794989    .269043    -2.15   0.031    -1.106813   -
> .0521843
> teach_hosp~l |   .1910294   .1522697     1.25   0.210    -.1074136
> .4894725
> percent_me~e |   .0176805   .0070849     2.50   0.013     .0037944
> .0315666
> percent_me~d |    .009975    .007018     1.42   0.155      -.00378
> .02373
>          cmi |   .5187269   .2819726     1.84   0.066    -.0339292
> 1.071383
> penalty_3025 |   .3618394   .1409491     2.57   0.010     .0855842
> .6380947
>        _cons |  -3.029929   .6463519    -4.69   0.000    -4.296755   -
> 1.763102
> --------------------------------------------------------------------------
> ----
> 
> 
> Rekha Varghese
> 
> 

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