Which statement best describes a cross-sectional study?

Which statement best describes a cross-sectional study?

• A. Follows subjects over time to observe outcomes
• B. Assigns exposure randomly
• C. Measures exposure and outcome at one point in time
• D. Assesses cause-effect by starting with diseased subjects and controls

Answer: (C)

A cross-sectional study captures information on exposure and outcome at a single point in time, providing a snapshot of a population. This design is useful for estimating how common a condition or exposure is and for exploring associations between factors and outcomes, but because both are measured simultaneously, it cannot establish which came first or prove causality. In contrast, following people over time describes a cohort (longitudinal) study; randomly assigning exposure describes a randomized controlled trial; and starting with diseased subjects and appropriate controls describes a case-control study.

A cross-sectional study captures information on exposure and outcome at a single point in time, providing a snapshot of a population. This design is useful for estimating how common a condition or exposure is and for exploring associations between factors and outcomes, but because both are measured simultaneously, it cannot establish which came first or prove causality. In contrast, following people over time describes a cohort (longitudinal) study; randomly assigning exposure describes a randomized controlled trial; and starting with diseased subjects and appropriate controls describes a case-control study.