Re: st: Graphic displays or results from margins

[Phil Schumm <pschumm@uchicago.edu>]

On Sep 20, 2010, at 10:32 AM, Richard Williams wrote:
> I am warming up to the new margins command.  However, unlike the  
> older adjust command, margins does not include the ability to  
> generate new variables. I am therefore finding it hard to create  
> graphic displays of the results.
>
> Consider the following:
>
> webuse nhanes2f, clear
> logit diabetes i.black i.female age i.female#c.age, nolog
> margins female#black, at(age = (20(10)70))
>
> I would love to create a graphic where the Y axis was the  
> probability of diabetes, the X axis was age, and there were 4  
> separate lines, for black males, black females, nonblack males,  
> nonblack females.


I believe that the only option currently is to go manually through  
e(b).  For example, if you add the -post- option to your -margins-  
command above, you could do something like this:


    mat A = e(b)'
    svmat A
    egen _age = fill(10 10 10 10 20 20 20 20)
    egen _grp = fill(1 2 3 4 1 2 3 4)
    separate A1, by(_grp)
    line A11-A14 _age if !mi(A1)


It wouldn't be difficult to write a little command to do this in a  
more general way (indeed, someone may have done it already).


-- Phil

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/