Understanding Study Design

Abstract

Medical studies use several common designs. Correctly naming a study’s design is not just an exercise in terminology but helps readers to evaluate the study’s level of evidence, limitations and biases, and statistical analyses. Analytic studies evaluate the association between a risk factor (eg, intervention, exposure) and the outcome. Studies fall into 2 overarching categories: observational and experimental. This article reviews the major analytic study designs, including their advantages and disadvantages, and their relevance for statistics (summarized in Table 1).