Kramer M S, Boivin J F
J Chronic Dis. 1987;40(7):683-8. doi: 10.1016/0021-9681(87)90104-4.
Existing classifications of research designs for epidemiologic studies are inconsistent and confusing because of the conceptual "confounding" of three distinct concepts: directionality in which exposure and outcome are investigated, sample selection criteria, and timing of the study proper with respect to the calendar times of exposure and outcome. The authors have attempted to construct a classification in which these three concepts comprise distinct (if not totally independent) axes. Closer attention to the distinctions described may help the planning and interpretation of epidemiologic studies, as well as facilitate future teaching and communication.
现有的流行病学研究设计分类存在不一致且令人困惑的问题，原因在于三个不同概念在概念上的“混淆”：研究暴露与结果的方向性、样本选择标准以及相对于暴露和结果的日历时间而言研究本身的时间安排。作者试图构建一种分类，其中这三个概念构成不同（即便并非完全独立）的轴。更加关注所描述的这些区别可能有助于流行病学研究的规划与解读，同时也便于未来的教学与交流。
