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From | Nils Braakmann <nilsbraakmann@googlemail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: A question about identification strategies |
Date | Thu, 1 Apr 2010 10:18:40 +0200 |
Dear Charlie, i'd say it depends on the question. A situation where I could imagine that this arguments makes sense: Say, you're interested in evaluating a training program where unemployed individuals are assigned to the program by some case worker based solely on information contained in some files (i.e., there's no personal contact between the case worker and the unemployed) and you have access to these files. In these cases, a claim that assingment is essentially random conditional on the information contained in the files might have some merit as the assignment mechanism should depend only on the information available to you. However, identification would still require the assumption that the remaining fluctuations in treatment assignment are essentially random, which might be still be violated if, for instance, treatments are assinged on a first come, first served base so that individuals who become unemployed at the beginning of the month are more likely to get treated (and this time difference matters for the outcomes). Hope this helps, Nils P.S.: I guess, Angrist (1998, "Estimating the Labor Market Impact of Voluntary Military Service Using Social Security Data on Military Applicants", Econometrica 66(2), pp. 249-288) uses a version of this argument in his first strategy. If I come across other references, I let you know. On Thu, Apr 1, 2010 at 4:20 AM, C Engelbrecht <cngelbrecht@gmail.com> wrote: > I read in a couple of working papers where the authors claim that they > "obtain all information presented to the agent", therefore they should > be able to claim causality using a simple OLS. I certainly sympathize > because IVs are hard to come by, but is this a valid argument? Have > you seen similar arguments made in published papers? > > Many thanks for any reference you can point me to. > > Charlie > * > * 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/