What is a limitation of cross-sectional studies?

Cross-sectional studies are designed to collect data at a single point in time, which provides a snapshot of a population or phenomenon. This inherent characteristic means that while researchers can observe relationships between variables at that moment, they cannot determine how these relationships evolve over time or if they are causal in nature. Causation implies directionality and temporal precedence, where one variable influences another over a period. Since cross-sectional studies lack this longitudinal perspective, they cannot establish whether a change in one factor precedes a change in another, which is essential for causal inference.

This limitation highlights why cross-sectional studies are often used for descriptive purposes or hypothesis generation rather than definitive conclusions about cause-and-effect relationships. The other options reflect different aspects of study design or data analysis but do not capture the essence of this limitation as accurately as the selected answer.