A New Non-Parametric Matching Method for Bias Adjustment with Applications to Economic Evaluations

48 Pages Posted: 23 Jun 2007 Last revised: 2 Jun 2008

See all articles by Jasjeet S. Sekhon

Jasjeet S. Sekhon

UC Berkeley

Richard Grieve

London School of Hygiene and Tropical Medicine

Date Written: May 11, 2008

Abstract

In health economic studies that use observational data, a key concern is how to adjust for imbalances in baseline covariates due to the non-random assignment of the programs under evaluation. Traditional methods of covariate adjustment such as regression and propensity score matching are model dependent and often fail to replicate the results of randomized controlled trials. We demonstrate a new non-parametric matching method, Genetic Matching, which is a generalization of propensity score and Mahalanobis distance matching (Sekhon forthcoming), using two contrasting case studies. In the first, an economic evaluation of a clinical intervention (Pulmonary Artery Catheterization), applying Genetic Matching to observational data replicates the substantive results of a corresponding randomized controlled trial unlike the extant literature. And in the second case study evaluating capitation versus fee-for-service, Genetic Matching radically improves balance on baseline covariates and overturns previous conclusions based on traditional methods.

Keywords: bias reduction, observational studies, economic evaluation, matching

JEL Classification: C14, C99, I10

Suggested Citation

Sekhon, Jasjeet S. and Grieve, Richard, A New Non-Parametric Matching Method for Bias Adjustment with Applications to Economic Evaluations (May 11, 2008). iHEA 2007 6th World Congress: Explorations in Health Economics Paper. Available at SSRN: https://ssrn.com/abstract=1138926 or http://dx.doi.org/10.2139/ssrn.1138926

Jasjeet S. Sekhon (Contact Author)

UC Berkeley ( email )

310 Barrows Hall
Berkeley, CA 94720
United States

Richard Grieve

London School of Hygiene and Tropical Medicine ( email )

Keppel Street
London, WC1E 7HT
United Kingdom

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