A research design that tracks the same individuals at multiple points in time is called a:

• A. Cross-sectional study
• B. Time-series study
• C. Longitudinal survey
• D. Field experiment

Answer: (C)

This design is a longitudinal survey because it follows the same individuals at multiple points in time, letting researchers observe how people change or how relationships between variables develop within the same person. By tracking the same participants, you can see patterns of growth, stability, or decline and establish the sequence of events, which helps with understanding causality and development over time.

This contrasts with a cross-sectional study, which collects data from different people at one moment, so it can’t show how one person changes. A time-series study looks at changes in a single variable over time, often focusing on aggregate data or measurements that may not follow the same individuals. A field experiment involves manipulating something in a real-world setting to observe effects, not necessarily tracking the same people over multiple time points.