Partly in response to criticism from the traditional medical specialties, partly to define and legitimize its mission, and partly to upgrade the quality and scope of its research efforts, primary care medicine has wholeheartedly embraced its own set of "hard sciences." Epidemiology and clinical epidemiology, biostatistics, clinical decision analysis, cost-benefit and cost-effectiveness analysis—these disciplines seem to contribute an ever-growing share to both the professional vocabulary and self-esteem of primary care physicians. In this setting of growing interest and expertise and a proliferating literature, we are now offered Practice-Based Epidemiology. How does this new arrival differ from its siblings? What can it offer the practitioner? The academic? Above all, is it worth the time and effort a thorough reading requires?
In reality, Schuman's book is not attempting to define new territory, but to restate fundamental epidemiologic principles in a way that makes them psychologically and professionally accessible to the clinician. This