Which study design assesses a population at a single point in time to determine prevalence?

• A. Retrospective
• B. Concurrent
• C. Cross-sectional
• D. Prospective

Answer: (C)

A cross-sectional study captures a population at one point in time to estimate how common a condition or attribute is—its prevalence. This design provides a snapshot of the current burden in the group, which is exactly what prevalence measures: the proportion of individuals who have the condition at that moment. It’s not about following people over time, so it doesn’t establish temporality or causality.

Retrospective designs look back over past records to connect exposures and outcomes that have already occurred, while prospective designs follow participants forward to observe what happens over time. Data collected at the same time can align with cross-sectional methods, but the defining feature here is the single-time snapshot used to determine prevalence.