Dealing with Limited Overlap in Estimation of Average Treatment Effects

Dealing with Limited Overlap in Estimation of Average Treatment Effects

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Dealing with Limited Overlap in Estimation of Average Treatment Effects

dc.contributor.author	Hotz, V. Joseph
dc.contributor.author	Crump, Richard K.
dc.contributor.author	Imbens, Guido
dc.contributor.author	Mitnik, Oscar A.
dc.date.accessioned	2009-05-28T15:40:04Z
dc.date.issued	2009
dc.identifier.citation	Crump, Richard K., V. Joseph Hotz, Guido W. Imbens, and Oscar A. Mitnik. 2009. Dealing with limited overlap in estimation of average treatment effects. Biometrika 96(1): 187-199.	en
dc.identifier.issn	0006-3444	en
dc.identifier.uri	http://nrs.harvard.edu/urn-3:HUL.InstRepos:3007645
dc.description.abstract	Estimation of average treatment effects under unconfounded or ignorable treatment assignment is often hampered by lack of overlap in the covariate distributions between treatment groups. This lack of overlap can lead to imprecise estimates, and can make commonly used estimators sensitive to the choice of specification. In such cases researchers have often used ad hoc methods for trimming the sample. We develop a systematic approach to addressing lack of overlap. We characterize optimal subsamples for which the average treatment effect can be estimated most precisely. Under some conditions, the optimal selection rules depend solely on the propensity score. For a wide range of distributions, a good approximation to the optimal rule is provided by the simple rule of thumb to discard all units with estimated propensity scores outside the range [0.1,0.9].	en
dc.description.sponsorship	Economics	en
dc.language.iso	en_US	en
dc.publisher	Oxford University Press	en
dc.relation.isversionof	http://dx.doi.org/10.1093/biomet/asn055	en
dc.relation.hasversion	http://ssrn.com/abstract=937912	en
dash.license	OAP
dc.subject	average treatment effect	en
dc.subject	causality	en
dc.subject	treatment effect heterogeneity	en
dc.subject	overlap	en
dc.subject	ignorable treatment assignment	en
dc.subject	propensity score	en
dc.subject	unconfoundedness	en
dc.title	Dealing with Limited Overlap in Estimation of Average Treatment Effects	en
dc.relation.journal	Biometrika	en
dash.depositing.author	Imbens, Guido