"While we can observe actual spending for ACO beneficiaries, ... it's very hard to know what would have been spent if ACOs did not exist. It is important to avoid using the [CMS] benchmarks to evaluate ACO savings because benchmarks are constructed with policy goals in mind.... Using the benchmark as the measure of success, analysts have concluded, for example, that CMS actually lost money (on the order of $200 million) in the ACO program and that it was a bad deal for CMS. Contrast this with a conclusion based on the use of a counterfactual designed for research purposes (and based on regional spending trends):"  MORE >>