st: predicting with probit

[Scott Cunningham <scunning@gmail.com>]

I have individual level data observed over three years.  An  
individual is considered a part of a "core" group if they had 5 or  
more sex partners in the last twelve months.  I am then going to see  
how geographic conditions affects core and non-core members' condom  
usage, but arguably condom usage and sex partners are jointly  
determined.  So, instead, I have been advised to estimate a reduced- 
form probit of "core" onto various exogenous determinants, and then  
based on that value of "core-hat" sort my sample into predicted in/ 
out categories, followed by my reduced form condom-use regressions  
onto each subsample.  Is there a post-estimation command that will  
allow me to do this? 
 
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