Fig. 2

Performances of the Average Treatment effect on the Treated (ATT) estimator on the matched sets obtained in each scenario of the primary set of Monte Carlo simulations. The top-left plot shows the relative bias, whereas the Root Mean Squared Error (RMSE) is shown in the top-right plot. On the bottom-left side, the 95 % Nominal Coverage (NC) obtained with the standard method is depicted, whereas on the bottom-right side the 95 % NC obtained with the Abadie-Imbens (AI) method is shown. On the x-axis, the level of oversampling is represented. Matching without and with replacement are identified by the colors. The shape of the dots distinguishes between weak and strong treatment assignment. The columns of the panel grids show the proportion of treated subjects in the dataset, whereas the rows show the sample size of the dataset