Evaluating Nonexperimental Estimators for Multiple Treatments: Evidence from Experimental Data

Carlos A. Flores () and Oscar Mitnik
Additional contact information
Carlos A. Flores: California Polytechnic State University

No 4451, IZA Discussion Papers from Institute of Labor Economics (IZA)

Abstract: This paper assesses the effectiveness of unconfoundedness-based estimators of mean effects for multiple or multivalued treatments in eliminating biases arising from nonrandom treatment assignment. We evaluate these multiple treatment estimators by simultaneously equalizing average outcomes among several control groups from a randomized experiment. We study linear regression estimators as well as partial mean and weighting estimators based on the generalized propensity score (GPS). We also study the use of the GPS in assessing the comparability of individuals among the different treatment groups, and propose a strategy to determine the overlap or common support region that is less stringent than those previously used in the literature. Our results show that in the multiple treatment setting there may be treatment groups for which it is extremely difficult to find valid comparison groups, and that the GPS plays a significant role in identifying those groups. In such situations, the estimators we consider perform poorly. However, their performance improves considerably once attention is restricted to those treatment groups with adequate overlap quality, with difference-in-difference estimators performing the best. Our results suggest that unconfoundedness-based estimators are a valuable econometric tool for evaluating multiple treatments, as long as the overlap quality is satisfactory.

Keywords: nonexperimental estimators; multiple treatments; generalized propensity score (search for similar items in EconPapers)
JEL-codes: C13 C14 C21 (search for similar items in EconPapers)
Pages: 53 pages
Date: 2009-09
New Economics Papers: this item is included in nep-ecm and nep-exp
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (12)

Published - revised version published as 'Comparing Treatments across Labor Markets: An Assessment of Nonexperimental Multiple-Treatment Strategies' in: Review of Economics and Statistics, 2013, 95(5), 1691-1707

Downloads: (external link)
https://docs.iza.org/dp4451.pdf (application/pdf)

Related works:
Working Paper: Evaluating Nonexperimental Estimators for Multiple Treatments: Evidence from Experimental Data (2009)
Working Paper: Evaluating Nonexperimental Estimators for Multiple Treatments: Evidence from Experimental Data (2009)
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:iza:izadps:dp4451

Ordering information: This working paper can be ordered from
IZA, Margard Ody, P.O. Box 7240, D-53072 Bonn, Germany

Access Statistics for this paper

More papers in IZA Discussion Papers from Institute of Labor Economics (IZA) IZA, P.O. Box 7240, D-53072 Bonn, Germany. Contact information at EDIRC.
Bibliographic data for series maintained by Holger Hinte ().