Your response must be at least 500 words in length. Discuss the different sources of epidemiologic data and what each is used for. Your response must be at least 200-400 words in length. Present the most important criteria for assessing the quality and utility of epidemiologic data? Explain why these criteria are so important. What is meant by an “experimental” approach in epidemiology? Provide at least one example of this approach. What is meant by an “observational” approach in epidemiology? Provide at least one example of this approach. *5. Three of the most important study designs in modern epidemiology are ecologic studies, cross-sectional studies, and case-control studies. Briefly explain each of these study designs. Also, for each design, present at least one example of a research scenario in which the design would be appropriate.