st: heckman 2-step parameter stability

["Fabio Soares" <fvsoares@hotmail.com>]

Dear statalisters,

I want to test the stability the parameters of a wage equation corrected for 
selectivity bias (using heckman 2-step) to changes in the exclusion 
restrictions of the first step. Does anyone know how to implement a minimum 
distance test of the stability of the parameters using stata?

Thank you,

Fabio

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