How accurate are existing physician profiling products used by health plans at predicting/identifying resources used by physicians and physician groups? Researchers at the University of Michigan evaluated these products to answer the following questions: 1) Do some physician profiling risk-adjustment methodologies produce more accurate profiles of physician practice efficiency than others? If so, how do the methodologies compare? 2) How does the number of patients managed by a physician affect the accuracy of the physician’s practice efficiency profile? and 3) Are differences in accuracy among profiling systems’ risk-adjustment methodologies large enough to affect rankings of physicians’ practice efficiency? How consistent are physician practice efficiency rankings from different profiling systems, and how consistent are the systems in identifying outlier physicians? As the researchers noted, physician-profiling information “can be used to select network providers, channel patients, and identify both exemplary practice styles and those that suggest a need for education. Also, reports indicate that profiles are used by health plans for identifying physicians for de-selection from networks.” The objective of this study was to evaluate the accuracy of the profiling methodologies being marketed to health plans and examine the implications of differences in accuracy among the tools.