Which statement about cross-sectional studies is true?

Which statement about cross-sectional studies is true?

• A. They can establish causality
• B. They are efficient and inexpensive
• C. They require long follow-up
• D. They track changes over time

Answer: (B)

Cross-sectional studies capture information on exposure and outcome at a single point in time, giving a quick snapshot of a population. Because they don’t involve following people over weeks or years, they’re typically efficient and inexpensive to run. The trade-off is that you can’t establish causality from them—temporal order isn’t known, so you can’t tell whether the exposure came before the outcome or vice versa. They also don’t track changes over time, which is a feature of longitudinal designs. So the statement that best describes cross-sectional studies is that they are efficient and inexpensive.

Cross-sectional studies capture information on exposure and outcome at a single point in time, giving a quick snapshot of a population. Because they don’t involve following people over weeks or years, they’re typically efficient and inexpensive to run. The trade-off is that you can’t establish causality from them—temporal order isn’t known, so you can’t tell whether the exposure came before the outcome or vice versa. They also don’t track changes over time, which is a feature of longitudinal designs. So the statement that best describes cross-sectional studies is that they are efficient and inexpensive.