This self-instructional manual on the interpretation and use of epidemiological data deals with the basic concepts and skills needed for the appraisal of published reports or one's own findings. Applications in clinical medicine, public health, community medicine, and research are all taken into consideration. This book is designed as a workbook of short exercises and instructional self-tests that introduce fundamental approaches and procedures in data interpretation and develop competency in working with basic epidemiological tools. Basic concepts are presented in the first section, which also demonstrates the step-by-step assessment of data. The next section discusses rates and other simple measures, and the third shows how to judge their accuracy. The fourth and fifth sections deal with more complex issues of associations between variables and the appraisal of cause-effect relationships. The last section, which is entirely new, deals with meta-analysis (the critical review and integration of the findings of separate studies.) Its aim is to provide readers with the basic skills required for making sense of the results of a set of studies and for appraising published reports of meta-analyses and deciding whether to use their results.