Deciding whether the conclusions of studies are justified: a review.

Critical review of original studies is a major source of medical information for the physician; it necessitates a clear understanding of the research objective of the study. The design of the study, whether experimental or observational, should be appropriate to answer the research question and, further, the study should employ accurate and precise measurements on a suitable group of subjects. The critical reader, aware of the principle of study design and analysis, can assess the validity of the author's conclusions through careful review of the article. A guide to the analysis of an original article is presented here. The reader is asked to formulate questions about a study from the abstract. The answers to these questions, which form the basis for acceptance or rejection of the author's conclusions, are in general available in the body of an article. This technique is demonstrated with two fictional studies about patients with angina.