Question

a hypothetical cohort study was undertaken among 600 adhd - free children in south carolina. the purpose of the study was to examine the effects of increased screen time during childhood on the subsequent diagnosis of adhd by young adulthood. the childrens screen time was assessed by a questionnaire, and the children were followed for 10 years. the following data were obtained from the study.
what measure of association is most appropriate given the study design?
a prevalence ratio
b relative risk
c odds ratio

Explanation:

• Prevalence Ratio: Used in cross - sectional studies to compare the prevalence of a disease or condition in different groups. This is a cohort study, not cross - sectional, so this is incorrect.
• Relative Risk: Appropriate for cohort studies. It measures the ratio of the risk of a disease (ADHD in this case) in the exposed group (screen time ≥ 4 hours) to the risk in the unexposed group (screen time < 4 hours).
• Odds Ratio: Commonly used in case - control studies.

Answer:

B. Relative risk