Application of the Generalized Propensity Score. Evaluation of public contributions to Piedmont enterprises.

In this article, we apply a generalization of the propensity score of Rosenbaum and Rubin (1983b). Techniques based on the propensity score have long been used for causal inference in observational studies for reducing bias caused by non-random treatment assignment. In last years, Joffe and Rosenbaum (1989) and Imbens and Hirano (2000) suggested two possible extensions to standard propensity score for ordinal and categorical treatments respectively. Propensity score techniques, allowing for continuous treatments effect evaluation, were, instead, recently proposed by Van Dick Imai (2003) and Imbens and Hirano (2004). We refer to Imbens' approach for the use of the generalized propensity score, to widen its application for continuous treatment regimes.