引言

流行病学是一门探讨影响人类群体健康及疾病的学问，是公共卫生及预防医学的矾石。它被视为公共卫生研究的基础方法论， 同时在循证医学中做为辨别疾病因素和最佳临床治疗途径的科学理论。

在研究传染病及非传染性疾病时，流行病学家从事众多事项，包含爆发调查、研究设计、数据搜集及分析（如创建统计模块）等。流行病学家须跨足并使用不同领域的知识，如生物学、生物计量学、地理信息系统和社会科学。

流行病学不仅研究传染病，其他如慢性病（像癌症、心脏病、糖尿病、高血压等等）、精神疾病、自杀与意外事件等等健康议题，甚至各种疾病的危险因子（如抽烟、肥胖、营养摄取状态、生活型态等），都可成为流行病学研究的主题。

Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare. Epidemiologists help with study design, collection, and statistical analysis of data, amend interpretation and dissemination of results (including peer review and occasional systematic review). Epidemiology has helped develop methodology used in clinical research, public health studies, and, to a lesser extent, basic research in the biological sciences.