st: RE: heckman model

["Vassilopoulos Achilleas" <vassilopoulos.statalist@gmail.com>]

Yes, rho is the correlation coefficient between the two residuals. As a matter of fact, lamda can be derived by multiplying rho with sigma (the standard error of the residual of the second stage).

Hope this helps,

_____________ - _______________

Achilleas Vassilopoulos

Agricultural University of Athens,
Dept. of Agricultural Economics and Rural Development, Lab. of Political Economy and European Integration.
Iera Odos 75, 11855, Athens, Greece

Tel: (+30) 210-5294726
Fax: (+30) 210-5294786
Email : avassilopoulos.aua@gmail.com


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of a.carrozzone@libero.it
Sent: 17 January, 2011 16:38
To: statalist@hsphsun2.harvard.edu
Subject: st: heckman model

Dear Stata users,

I have a doubt regarding the Heckman procedure (heckman command).

Why is the estimate of rho different than the estimated coefficient of  
lambda? Is rho here defined as the correlation coefficient between the 
estimated residuals of the two equations?

Thanks a lot,


Andrea
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