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  • Understanding Margins with a Fractional Proportion DV

    Hi All,
    I have a proportion DV. I can't use the
    Code:
    fracreg
    command because of my unit of analysis, so my regression is as follows:

    Code:
    xtgee y i.x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12, family(binomial 1) link(probit) corr(exchangeable) vce(robust)
    I have a variable that I'm in interested in analyzing, x1, which is a binary variable coded as 0/1.

    I found the link on fractional models (https://www.stata.com/stata14/fracti...utcome-models/) and dyex is used for margins. I tried to use dyex, but I couldn't, because it says factor variables not allowed with dyex. So, I decided to use
    Code:
    margins, dydx(*)  margins x1
    I received the below results:
    Code:
    margins x1
    
    Predictive margins                              Number of obs     =     13,405
    Model VCE    : Semirobust
    
    Expression   : Pr(y != 0), predict()
    
    ------------------------------------------------------------------------------
                 |            Delta-method
                 |     Margin   Std. Err.      z    P>|z|     [95% Conf. Interval]
    -------------+----------------------------------------------------------------
              x1 |
              0  |   .2681136   .0049269    54.42   0.000     .2584571    .2777702
              1  |   .3810374   .0503208     7.57   0.000     .2824105    .4796644
    ------------------------------------------------------------------------------
    I had asked this question before, but now I'm wondering how to interpret the margin results above after finding this post (granted it's for a continuous variable)-- (https://www.statalist.org/forums/for...uous-variables).

    Does this read that when x goes from 0 to 1 the proportion (y) increases by 11.3%? I found Richard Williams's Slides https://www3.nd.edu/~rwilliam/stats/Margins01.pdf. Are average marginal effects the same thing as average partial effects?

    Lastly, I'm obviously not well-versed in econometrics, but is there another way to interpret the results of x1? With the margin command (EDIT: Or is it because of the regression?), if I interpreted correctly, it reads from 0 to 1 (for lack of better words). Is there a way to read the results as when x=1 (yes) or when x=0 (no) not as "when no goes to yes." (Again, sorry for the layman's terms. I gladly welcome better terminology).

    Thank you.
    Last edited by Monica White; 19 Mar 2019, 17:12. Reason: Added extra question after "EDIT:"
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