Identification and Estimation of Causal Effects of Multiple Treatments Under the Conditional Independence Assumption

Abstract

The assumption that the assignment to treatments is ignorable conditional on attributes plays an important role in the applied statistic and econometric evaluation literature. Another term for it is conditional independence assumption. This paper discusses identification when there are more than two types of mutually exclusive treatments. It turns out that similar to the case of only two types of treatments extensions of the classical balancing score properties involving now multivariate balancing scores can be used for identification. Therefore, a similar reduction of dimension is achieved and the approach retains its basic simplicity. The paper also outlines a matching estimator potentially suitable in that framework.

JEL Classification: C30, C40