This course builds on introductory knowledge in epidemiology. This course builds upon the basic principles and methods of epidemiology and introduces additional tools and concepts that are critical to a comprehensive study design. Topics include: risk and association, sampling strategies, interaction, confounding, adjustment, causal inference, validity and reliability and approaches to data analysis. Specifically, this course revises descriptive data collection and analysis in epidemiology. This course guides students to the design, conduct, and interpretation of observational epidemiologic and clinical studies in human populations with a focus on analytic cohort, case-control, and cross-sectional studies. Comparisons with randomized controlled trials (RCTs) will be made with discussion of the advantages and disadvantages of the different study designs for specific epidemiologic and clinical research questions.It covers elementary standardization of crude rates and ratios.