Stephen L. Morgan and David J. Harding, Matching Estimators of Causal Effects: Prospects and Pitfalls in Theory and Practice, Sociological Methods & Research 2006 35: 3-60.

February 7, 2010
As the counterfactual model of causality has increased in popularity, sociologists have returned to matching as a research methodology. In this article, advances over the past two decades in matching estimators are explained, and the practical limitations of matching techniques are emphasized. The authors introduce matching methods by focusing first on ideal scenarios in which stratification and weighting procedures warrant causal inference. Then, they discuss how matching is often undertaken in practice, offering an overview of the most prominent data analysis routines. With four hypothetical examples, they demonstrate how the assumptions behind matching estimators often break down in practice. Even so, the authors argue that matching techniques can be used effectively to strengthen the prosecution of causal questions in sociology.

Key Words: matching methods • matching techniques • stratification • causal effects