Propensity Score Matching Methods for Non-Experimental Causal Studies

Columbia University Economics Department Discussion Paper No. 0102-14

40 Pages Posted: 12 May 2012

See all articles by Rajeev H. Dehejia

Rajeev H. Dehejia

New York University (NYU) - Robert F. Wagner Graduate School of Public Service; National Bureau of Economic Research (NBER); Institute for the Study of Labor (IZA); CESifo

Sadek Wahba

Morgan Stanley

Multiple version iconThere are 2 versions of this paper

Date Written: February 1, 2002

Abstract

This paper considers causal inference and sample selection bias in non-experimental settings in which: (i) few units in the non-experimental comparison group are comparable to the treatment units; and (ii) selecting a subset of comparison units similar to the treatment units is difficult because units must be compared across a high-dimensional set of pretreatment characteristics. We discuss the use of propensity score matching methods, and implement them using data from the NSW experiment. Following Lalonde (1986), we pair the experimental treated units with non-experimental comparison units from the CPS and PSID, and compare the estimates of the treatment effect obtained using our methods to the benchmark results from the experiment. For both comparison groups, we show that the methods succeed in focusing attention on the small subset of the comparison units comparable to the treated units and, hence, in alleviating the bias due to systematic differences between the treated and comparison units.

Keywords: Matching, Observational Studies, Program Evaluation, Propensity Score, Training Programs

JEL Classification: C14, C81, C99, H53, I38

Suggested Citation

Dehejia, Rajeev H. and Wahba, Sadek, Propensity Score Matching Methods for Non-Experimental Causal Studies (February 1, 2002). Columbia University Economics Department Discussion Paper No. 0102-14. Available at SSRN: https://ssrn.com/abstract=1084955 or http://dx.doi.org/10.2139/ssrn.1084955

Rajeev H. Dehejia (Contact Author)

New York University (NYU) - Robert F. Wagner Graduate School of Public Service ( email )

The Puck Building
295 Lafayette Street, Second Floor
New York, NY 10012
United States

HOME PAGE: http://users.nber.org/~rdehejia/

National Bureau of Economic Research (NBER) ( email )

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

HOME PAGE: http://users.nber.org/~rdehejia/

Institute for the Study of Labor (IZA) ( email )

P.O. Box 7240
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Germany

CESifo ( email )

Poschinger Str. 5
Munich, DE-81679
Germany

Sadek Wahba

Morgan Stanley ( email )

1585 Broadway
New York, NY 10036
United States

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