Answer:
Research that compares two groups of people: those who have the disease or condition being studied (cases) and those who do not have the disease or condition (controls) (controls). A retrospective cohort study, also known as a historic cohort study, is a type of longitudinal cohort study that is commonly employed in medical and psychological research. A retrospective study makes use of previously recorded data for causes other than research. A retrospective case series is a collection of instances involving a novel or unique disease or treatment.