Before revision: This article extends the method of synthetic controls to probability measures. The distribution of the synthetic control group is obtained as the optimally weighted barycenter in Wasserstein space of the distributions of the control groups which minimizes the distance to the distribution of the treatment group. It can be applied to settings with disaggregated- or aggregated (functional ) data .
After revision: This article introduces a generalization of the widely-used synthetic controls estimator for evaluating causal effects of policy changes. The proposed method can be applied to settings with disaggregated- or aggregated (functional ) data .