Question: Research studies can be divided into three types of studies- experimental, quasi-experimental, and observational. In epidemiology, most of the studies are observational. Observational studies can be either analytic or descriptive. Analytic studies can help provide information about disease etiology and also support preventative measures in public health. This week we examine ecologic, cross-sectional, and case-control studies. Compare and contrast these types of studies in terms of epidemiology. Give the strengths and limitations of these types of studies as well as what they are used for in research. Provide examples of each type of study that you find in the literature.