\% CEM: A SAS Macro to perform Coarsened Exact Matching

%CEM is a SAS macro which allows researchers to perform the recently introduced Coarsened Exact Matching (CEM) technique. CEM is a non-parametric matching method to avoid the confounding influence of pre-treatment control variables directly improving causal inference in quasi experimental studies. The %CEM macro introduces a completely automated process wich allows SAS users to perform an exact matching over massive data. Several matching strategies automatically test the population’s imbalance providing the optimal variables binning an associated L1 imbalance measure. An empirical application estimating the causal effect of regional health systems on the intra-hospital mortality using multiple administrative datasets from a large regional database completes the paper.