What is a key limitation of cross-sectional studies?

• A. They cannot establish temporality between exposure and outcome.
• B. They require temporal sequencing of exposure.
• C. They determine the incidence of disease.
• D. They allow randomization of exposure.

Answer: (A)

Cross-sectional studies capture exposure and disease status at a single point in time, so temporality cannot be established. Because both exposure and outcome are measured together, you can’t tell which came first, making it impossible to infer causality—only associations. This design is useful for estimating how common a condition or exposure is (prevalence) and for generating hypotheses, but it can’t determine incidence or prove that exposure causes disease.