Dear Stata Users,

I am applying the two step Heckmam model, but I am having a problem.

After having completed the Heckman model.

As further check I have tried to perform the probit model (decision equation of Heckman procedure).

However, even though I use exactly the same variables, the coefficients of some independent v. and pvalues are completely different from those obtained with Heckman.

I have already Heckman in past, but It is the first time i meet this problem.

If someone can help, I will strongly appreciate

thanks in advance

Nicola


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