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  • .areg with variables of interaction

    Greetings,

    I'm Alessandro and I'm new at the community and at Stata, thus I apologize for any mistake I possibly make in this post.

    I have an activity at college where I should try to replicate the regression from the Mincer-based model below. I gathered all the information needed, and now I'm trying to figure which is the best way to make the regression:



    So, firstly I tryed to make a simple .regress using all the variables as factor, like this:


    Code:
    regress logie i.year##(i.age3##i.edattain i.micr)
    
          Source |       SS       df       MS              Number of obs =   19368
    -------------+------------------------------           F(1616, 17751) =  247.41
           Model |  12091.0481  1616   7.4820842           Prob > F      =  0.0000
        Residual |  536.822207 17751  .030241801           R-squared     =  0.9575
    -------------+------------------------------           Adj R-squared =  0.9536
           Total |  12627.8703 19367  .652030272           Root MSE      =   .1739
    
    -----------------------------------------------------------------------------------------------
                            logie |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
    ------------------------------+----------------------------------------------------------------
                             year |
                            2000  |   .7381118   .1104081     6.69   0.000     .5217013    .9545224
                            2010  |   1.071136   .0997068    10.74   0.000     .8757009    1.266571
                                  |
                             age3 |
                              20  |   .3379559   .0107893    31.32   0.000     .3168079    .3591039
                              30  |    .491482   .0108114    45.46   0.000     .4702906    .5126734
                              40  |    .379497   .0108421    35.00   0.000     .3582454    .4007486
                                  |
                         edattain |
               Primary completed  |   .3042252   .0109946    27.67   0.000     .2826747    .3257756
             Secondary completed  |   .8034804   .0117411    68.43   0.000     .7804668    .8264941
    --more--
    To do that I had to reset the matsize. And I don't think this is the right way to make it work.

    So, I tryed doing the .xtreg, based on the panel options, with fixed effects (also random, to make sure) both didn't work: Not enough observations.

    Then, I found the .areg, which I think may be the right way to do it. I tryed like this:

    Code:
    areg logie i.year##(i.age3##i.edattain), abs(micr)
    
    Linear regression, absorbing indicators           Number of obs   =      19368
                                                      F(  47,  18797) =    6241.16
                                                      Prob > F        =     0.0000
                                                      R-squared       =     0.9503
                                                      Adj R-squared   =     0.9488
                                                      Root MSE        =     0.1828
    
    -----------------------------------------------------------------------------------------------
                            logie |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
    ------------------------------+----------------------------------------------------------------
                             year |
                            2000  |   .6260014   .0113266    55.27   0.000     .6038002    .6482026
                            2010  |   .9427891   .0113664    82.95   0.000       .92051    .9650682
                                  |
                             age3 |
                              20  |--Break--
    r(1);
    
    .
    But this one probably isn't considering the interaction between "micr" and "year".

    Based on this and my limited skills I have the following questions: i) There is a way to consider the interaction between the absorbed indicator and other variable? ii) Could you indicate if .areg is actually a good way to regress this model or there is another way to do it more efficiently?

    I would aprecciate any help or comment.

    Thank you and have a good day!!!

  • #2
    I would also like to add that it is a really short time period (only 3 censos/years).

    Comment


    • #3
      First, if you want fixed effects, regress with i.panel, areg, and xtreg,fe should give you identical results. Are you trying to do interactions with the absorbed/panel variable?

      If the i.panel estimate worked in regress, it should have worked in xtreg,fe. I suspect you have a typo. Also, areg should do interactions, but I'm not sure about interactions with the absorbed factor.

      If regress worked with the interactions you want, there is nothing wrong with that.

      Comment

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