ECONOMETRICS LECTURE: HECKMAN’s SAMPLE SELECTION …

Above calculate predicted value from regression (equivalent to . Ziγ in (2)) replace p1=-p1. Above calculates - Ziγ. generate phi = (1/sqrt(2*_pi))*exp(-(p1^2/2)) This is the normal distribution density function: phi is equivalent to . φ(-Ziγ) in (11) generate capphi = normal(p1) This is the cumulative debsity function: capphi is equivalent ... ................
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