Propensity Score Matching Methods for Non-experimental Causal Studies

Rajeev Dehejia () and Sadek Wahba

No 6829, NBER Working Papers from National Bureau of Economic Research, Inc

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 pre-treatment characteristics. We propose 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. 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.

JEL-codes: C81 C14 (search for similar items in EconPapers)
Date: Written 1998-12
Note: LS
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Published as Dehejia, Rajeev H. and Sadek Wahba. "Propensity Score-Matching Methods For Nonexperimental Causal Studies," Review of Economics and Statistics, 2002, v84(1,Feb), 151-161.

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Related works:
Working Paper: Propensity Score Matching Methods for Non-Experimental Causal Studies (1998)
Working Paper: Propensity score matching methods for non-experimental causal studies (2002)
Journal Article: Propensity Score-Matching Methods For Nonexperimental Causal Studies (2002)
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