st: RE: RE: exact matches in propensity score matching

["Millimet, Daniel" <millimet@mail.smu.edu>]

Psmatch2 does not have this sort of option.  You would have to code it by hand... e.g., restrict the sample to a given industry-year combination, apply psmatch2 to get the match and keep track of the estimated missing counterfactual, and then loop over all industry-year cells to build up the complete, matched data set.  Then you can compute average treatment effects.  You would need to bootstrap the entire process to get the standard errors (which is probably not acceptable if you use single nearest neighbor matching).  Note also that in this algorithm, you would probably want to estimate a single propensity score model for the entire sample and just feed this into psmatch2, rather than letting it estimate a different model for each sub-sample.

****************************************************
Daniel L. Millimet, Professor
Department of Economics
Box 0496
SMU
Dallas, TX 75275-0496
phone: 214.768.3269
fax: 214.768.1821
web: http://faculty.smu.edu/millimet
****************************************************


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Yang, Yong
Sent: Friday, June 22, 2012 12:33 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: exact matches in propensity score matching 

STATA code I am using is as followings, but do not know how to restrict them within industry and same year.

psmatch2  exporter employees employees2 capital capital2 industry_* year_*, out(sales) common  neighbor(1)

I really appreciate your time and advice.

Thank you in advance.

Regards
Yong

________________________________
From: Yang, Yong
Sent: 22 June 2012 18:19
To: 'statalist@hsphsun2.harvard.edu'
Subject: RE: exact matches in propensity score matching


Dear Stata users,



I am using propensity score matching estimator to find matched exporters and domestic firms, and estimate the sales differences between them.



However, I not sure how to restrict matched exporter and domestic firms in the same industry and same year in the matching exercise?  I want to match an exporter A with domestic firm B who have smallest propensity score difference and they have to be in same industry and appear in the same year.



Do you have any suggestion on this ?



Best regards



Yong



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