A cohort study is a longitudinal investigation in which the researcher identifies a group of subjects who do not yet have the outcome of interest. Which statement correctly describes this design?

A cohort study is a longitudinal investigation in which the researcher identifies a group of subjects who do not yet have the outcome of interest. Which statement correctly describes this design?

• A. It starts with individuals with the outcome
• B. It randomizes exposure
• C. It follows exposed and unexposed groups over time to observe outcomes
• D. It measures prevalence in a population at a single time

Answer: (C)

A cohort study is a longitudinal design that begins with a group of individuals who do not have the outcome of interest and then follows them over time to see who develops it. The statement that best describes this design is that it follows groups defined by exposure status (exposed and unexposed) over time to observe outcomes. This setup allows you to observe incidence and compare risk between the exposed and unexposed groups, and it can be prospective (following people forward in time) or retrospective (using existing records to look back). This differs from starting with people who already have the outcome (case-control) or measuring exposure and outcome at a single moment in time (cross-sectional), and it differs from randomizing exposure (an experimental trial).

A cohort study is a longitudinal design that begins with a group of individuals who do not have the outcome of interest and then follows them over time to see who develops it. The statement that best describes this design is that it follows groups defined by exposure status (exposed and unexposed) over time to observe outcomes. This setup allows you to observe incidence and compare risk between the exposed and unexposed groups, and it can be prospective (following people forward in time) or retrospective (using existing records to look back). This differs from starting with people who already have the outcome (case-control) or measuring exposure and outcome at a single moment in time (cross-sectional), and it differs from randomizing exposure (an experimental trial).