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  • Help with interpretation - psmatch2

    Dear STATA gurus!

    I have been reading this forum for days, and have yet to fully understand how psmatch2 can be interpreted. I will provide everything I have here. Thank y'all in advance.

    I run the following command:

    Code:
    psmatch2 ffs export_ipri year_control emplognew capitinv i.fyear i.gsector, outcome(lateROA) noreplacement
    I get the following results:

    Code:
    Probit regression                                       Number of obs =  9,182
                                                            LR chi2(26)   = 459.97
                                                            Prob > chi2   = 0.0000
    Log likelihood = -2837.1257                             Pseudo R2     = 0.0750
    
    ------------------------------------------------------------------------------
             ffs | Coefficient  Std. err.      z    P>|z|     [95% conf. interval]
    -------------+----------------------------------------------------------------
     export_ipri |  -.0168623   .0085528    -1.97   0.049    -.0336256   -.0000991
    year_control |  -.0049055   .0005325    -9.21   0.000    -.0059492   -.0038619
       emplognew |  -.0358342   .0120888    -2.96   0.003    -.0595279   -.0121405
        capitinv |   .1667146   .1296518     1.29   0.198    -.0873982    .4208273
                 |
           fyear |
           2008  |    .027891   .1502858     0.19   0.853    -.2666638    .3224458
           2009  |   .0705865    .149435     0.47   0.637    -.2223007    .3634737
           2010  |   .0708849   .1466351     0.48   0.629    -.2165146    .3582844
           2011  |   .0984372    .126006     0.78   0.435      -.14853    .3454043
           2012  |  -.0208677   .1272739    -0.16   0.870      -.27032    .2285846
           2013  |    .039797   .1265287     0.31   0.753    -.2081947    .2877886
           2014  |  -.0275057   .1279527    -0.21   0.830    -.2782884    .2232769
           2015  |  -.0097454   .1280022    -0.08   0.939     -.260625    .2411343
           2016  |    -.10004   .1290941    -0.77   0.438    -.3530598    .1529798
           2017  |  -.1036191   .1292263    -0.80   0.423    -.3568979    .1496597
           2018  |   .1134629   .1204432     0.94   0.346    -.1226015    .3495273
           2019  |    .053735   .1229188     0.44   0.662    -.1871815    .2946515
                 |
         gsector |
             15  |   .2415728   .1198503     2.02   0.044     .0066706    .4764751
             20  |    .205864   .1093709     1.88   0.060    -.0084989     .420227
             25  |   .7184278   .1097162     6.55   0.000      .503388    .9334677
             30  |   .9132355   .1197168     7.63   0.000      .678595    1.147876
             35  |  -.0202379    .116347    -0.17   0.862    -.2482738     .207798
             40  |   .1536092   .1311221     1.17   0.241    -.1033855    .4106038
             45  |   .1611879   .1079818     1.49   0.136    -.0504525    .3728283
             50  |   .9800344   .1233752     7.94   0.000     .7382234    1.221845
             55  |  -.2942186   .3381075    -0.87   0.384     -.956897    .3684599
             60  |   .2228457   .2027682     1.10   0.272    -.1745727    .6202641
                 |
           _cons |  -1.242982    .157199    -7.91   0.000    -1.551086   -.9348774
    ------------------------------------------------------------------------------
    ----------------------------------------------------------------------------------------
            Variable     Sample |    Treated     Controls   Difference         S.E.   T-stat
    ----------------------------+-----------------------------------------------------------
             lateROA  Unmatched | .034948008   .035744586  -.000796577      .004373    -0.18
                            ATT | .034948008   .030707496   .004240513   .006855752     0.62
    ----------------------------+-----------------------------------------------------------
    Note: S.E. does not take into account that the propensity score is estimated.
    
               | psmatch2:
     psmatch2: |   Common
     Treatment |  support
    assignment | On suppor |     Total
    -----------+-----------+----------
     Untreated |     8,226 |     8,226 
       Treated |       956 |       956 
    -----------+-----------+----------
         Total |     9,182 |     9,182
    Next, I look at ATT. Treated .0349 and controls .03070. There is a POSITIVE difference and it is significant.

    "ffs" is my binary 0/1 variable. I then say that when the value is 1, the effect is stronger; otherwise, weaker.

    So my first question: Is the above statement correct?

    Next, "export_ipri" variable is my interaction variable (IV multiplied by moderator). So what I want to find is whether the effect of my moderator differs on the outcome (lateROA) depending on the value of "ffs."

    So the second question: In psmatch2 do I need to include the IV as well? (the IV is "export" the moderator is "ipri").

    The third question: Would be it right to argue that the effect of "export_ipri" on my outcome (lateROA) is stronger when "ffs" = 1 (since the ATT is significant and the difference is positive). If so, then would it be correct to interpret it in this way: the effect of "export_ipri" is negative (and significant) on lateROA and it is MORE negative (stronger effect) when "ffs" = 1?

    The fourth question: Do I even care if anything is significant in that probit model? (in this case specifically "export_ipri")

    Thank you so much for your help. I have been reading everything for days and have yet to find the answers to the above questions.

    Happy Holidays!
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