Written to meet the needs of medical students and experienced clinicians alike, this book is a clearly presented, step-by-step guide to understanding how, through the processes of decision analysis, a physician can reach valid, reasoned conclusions about medical treatment despite imperfect information about the patient. The authors make extensive use of clinical examples to illustrate Bayesian analysis, formal decision analysis, and basic concepts of how to evaluate the usefulness of diagnostic tests in various situations. The text is supplemented with many illustrations, useful end-of-chapter self-assessment questions, an appendix giving the sensitivity and specificity of nearly 100 diagnostic tests, and a selective annotated bibliography directing the reader to significant articles in the current literature.