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Cohort Study is an observational study in which a group of individuals â a cohort â are followed over a period of time in order to determine either the incidence rate of certain diseases or the risk factors that lead to those diseases. These studies can be either prospective or retrospective.
Correlational research is a process in which variables are not manipulated, but. relationships between two or more variables are measured and investigated. B. In experimental research, one or more variables are manipulated, and scientists look. for a relationship between manipulation and changes in behavior.