An ecologic comparison study (aka a cross-sectional ecologic study) assesses the correlation between exposure rates and disease rates among different groups or populations over the same period of time. What is the purpose of an ecologic comparison study?
1) To determine the causality between exposure rates and disease rates
2) To compare the effectiveness of different treatments for a specific disease
3) To analyze the impact of environmental factors on disease rates
4) To study the prevalence of diseases in different populations