Changes in the financing and delivery of health care in the 1980s, originally driven by ever-escalating costs, led to increasing demands for accountability from providers to payers and consumers. The inability of the health care industry to articulate a vision, or even a definition of quality of care, allowed the promulgation of the use of extant data sources (claims data) in efforts to define quality. Although such data sources are limited in their ability to measure quality of care, the application of increasingly sophisticated computer algorithms has led to widespread public reporting of such information and a need for physicians to understand and participate in efforts to measure and report outcomes of medical interventions.