Researchers of comparative health systems have a tough job. Unable to resist the attraction of learning from abroad but also necessarily dubious of the validity of systems comparisons having so many confounding factors, such researchers push deeper into the mine, trying to keep each new discovery in context. Experts in national health policies know that these policies cannot be fully understood without also knowing what takes place at the level of the patient-physician interaction. Given that no person or group can study all of these levels, different research groups study the horizontal and vertical components of health systems, ideally leading to an aggregate picture that improves understanding and policy.
Chinitz D. Health Care in World Cities: New York, Paris, and London. JAMA. 2011;305(9):942-946. doi:10.1001/jama.2011.232