Since publication of the first three editions of this hugely successful book, systematic methods of critical appraisal have been accepted as central to healthcare provision, both in critical applications and in a wider health services and community perspective. This new edition builds on the work of the previous editions by presenting a fully updated and accessible system of critical appraisal applicable to clinical, epidemiological, and public health studies, and related fields.The book outlines the systematic review process for the establishment of causal effect within single and multiple studies. Focusing primarily on study design, it covers randomized and non-randomized trials, cohort studies, case-control studies, and surveys, showing the presentation of results including person-time and survival analysis, and issues in the selection of subjects. It then describes the process of detection and assessment of selection biases, observation bias, confounding, chance variation, and how to determine internal validity and external validity (generalizability). Statistical methods are presented in an accessible way, illustrating applications to each study design. Positive features of causation including strength, dose-response, and consistency are also discussed. The final chapters provide six examples of critical appraisals of major studies, encompassing randomized trials, prospective and retrospective cohort studies, and case-control studies. Statistical issues are explained clearly without complex mathematics, and the most useful methods are summarized in the appendix, each with a worked example. Each main chapter includes self-test questions, with answers provided, making the book ideally suited to readers with no prior epidemiological or statistical knowledge.Developed over four editions, Critical Appraisal of Epidemiological Studies and Clinical Trials is an invaluable aid to the effective assessment of new studies in epidemiology, public health, research methods, evidence-based methods, clinical medicine, and environmental health; making it essential reading for postgraduates, practitioners, and policymakers in these fields.