Focuses on areas of public health practice in which the systematic application of epidemiologic methods can have a large and positive impact. It describes how best to apply traditional epidemiologic methods for determining disease etiology to "real-life" problems in public health and health services research. The authors bridge the gap between theoretical epidemiology and public health practice, and covers a number of topics not addressed by other epidemiology texts with a focus on methods. This second edition contains a new chapter on the development and use of systematic reviews and one on epidemiology and the law.