Certified in Public Health (CPH) Practice Exam

Which statement is FALSE about prospective and retrospective cohort studies?

1. They measure the incidence of disease

2. They allow assessment of possible associations between exposure and outcomes

3. They require manipulation of the exposure of interest

4. They avoid bias from premature outcome knowledge

The correct answer is: They require manipulation of the exposure of interest

In prospective and retrospective cohort studies, researchers observe subjects over time in relation to their exposure to certain risk factors and then track outcomes like disease incidence. The key aspect of these studies is that they are observational in nature, meaning researchers do not manipulate or control the exposure. Cohort studies can effectively measure the incidence of disease and assess possible associations between exposures and outcomes without intervening in how participants are exposed. This characteristic allows researchers to draw conclusions about natural relationships between exposures and outcomes, which would not be possible if the exposure were manipulated by the researchers. Manipulating the exposure is a defining characteristic of experimental studies, such as randomized controlled trials. In contrast, cohort studies rely on observing outcomes based on existing exposure conditions, which makes option C the only inaccurate statement among the choices provided. Thus, the assertion that these studies require manipulation of the exposure is false.