Which statement best describes a strength of longitudinal designs?

• A. They track the same individuals over time to reveal development.
• B. They allow quick snapshots across different cohorts.
• C. They provide rich data on developmental trajectories across years.
• D. They are inexpensive and easy to conduct.

Answer: (C)

Longitudinal designs shine because they reveal how individuals change over time. By following the same people across multiple years, researchers can map developmental trajectories—seeing patterns of growth, stability, or decline within each person and comparing those patterns across the group. This within-person change data provides rich detail about how development unfolds, not just a single point in time.

While tracking the same individuals is a key feature, the strength is the depth of information about trajectories across years. In contrast, short-term or cross-sectional studies give quick snapshots across different groups but can’t show how a person’s development unfolds over time. Longitudinal research is also typically more resource-intensive and time-consuming, so it’s not described as inexpensive or easy.