Book excerpt: "The Lancet Handbook of Essential Concepts in Clinical Research speaks to two audiences: those who read and those who conduct research. Clinicians are medical detectives by training. For each patient, they assemble clinical clues to establish causes (e.g. diagnoses) of signs and symptoms. The task involves both clinical acumen and knowledge of medical research. This book helps guide clinicians through this detective work, by enabling them to make sense of research and to review medical literature critically. It will also be invaluable to researchers who conduct clinical research, particularly randomized controlled trials. Building on previously published, peer-reviewed articles from The Lancet, this handbook is essential for busy clinicians and active researchers interested in research methods."--BOOK JACKET.