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From | Fernando Rios Avila <f.rios.a@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: twostep option heckman |
Date | Wed, 27 Nov 2013 15:18:22 -0500 |
Hi Chiara, Keep in mind that the MLE estimates assume the errors from the probit and ols are simultaneously normal. Whereas the twostep one relaxes this assumption. As far as I know, mle is more efficient, but twostep is consistent. Hope this help. HTH On Wed, Nov 27, 2013 at 2:40 PM, Chiara Mussida <cmussida@gmail.com> wrote: > dear all, > if the heckman model for selection does not converge (not concave) the > option twostep allows getting consistent mle estimates. Are these > estimates reliable even if, as said, the model without the option > twostep does not converge? > Thanks for any kind of clarification. > Best > chiara > > -- > Chiara Mussida > Assistant Professor > Department of Economics and Social Sciences, > Università Cattolica del Sacro Cuore, > Piacenza (Italy) > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/