"Shared savings lie at the core of many recent health care payment and delivery reforms, most prominently those involving accountable care organizations (ACOs).... Although the main conclusions often overlap, there are times when administrative formulas and research-based evaluations can produce strikingly different results, provoking substantial confusion and consternation among stakeholders. This post looks at the advantages and disadvantages of the two approaches and discusses how they can be melded to best serve administrative, payment, and research needs."