What is a cross-sectional study?

• A. Follows the same individuals over time.
• B. A longitudinal survey design.
• C. A qualitative study.
• D. A study that compares individuals of different ages at one point in time.

Answer: (D)

A cross-sectional study compares individuals of different ages at a single point in time. This provides a quick “snapshot” of how variables differ across age groups, without following people over years. That’s why describing the approach as comparing different ages at one moment fits best. In contrast, following the same individuals over time is a longitudinal approach, which tracks change within the same people. A longitudinal survey design refers to that same idea of repeated observations over time. A qualitative study focuses on in-depth, non-numeric data and isn’t defined by comparing age groups at one moment. A key limitation of cross-sectional designs is that observed differences across ages may reflect cohort effects—generational differences—rather than development within individuals.