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From | "Michael Palmer" <Michael.Palmer@anu.edu.au> |
To | <statalist@hsphsun2.harvard.edu> |
Subject | RE: st: FW: Marginal effects for the two-part model |
Date | Wed, 2 Feb 2011 16:25:09 +1100 |
Thanks Maarten, I also thought this was the case (independent me) until I read a few papers that argue otherwise. See for example, http://repec.rwi-essen.de/files/REP_09_138.pdf. Cheers, Michael Michael Palmer PhD Candidate National Centre for Epidemiology and Population Health The Australian National University Ph. 6125 0538 M. 0437 867 940 -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten buis Sent: Tuesday, 1 February 2011 6:59 PM To: statalist@hsphsun2.harvard.edu Subject: RE: st: FW: Marginal effects for the two-part model --- On Tue, 1/2/11, Michael Palmer wrote: > The first part of the model is logit model for seeking hospital care > followed by an ols model for the cost of care for persons that sought > care. > > Simplified code is: > > Logit care $xvar, robust > > Reg cost $xvar if care==1 > > I am wanting to compute the conditional marginal effects but do not > know how to do this. In this model the cost is independent of seeking care, so the marginal effects of $xvar on the cost conditional on seeking care are just your regression coefficients (the output you got from -regress-). Typically, when estimating both parts you would want to allow for correlation in the error terms across your two steps. I tend to think of those correlations as variables that influence both the probability of seeking care and the cost and are not in $xvar. If that is what you want, then you can take a look at -help heckman-. Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/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/statalist/faq * http://www.ats.ucla.edu/stat/stata/