Longitudinal repeated measures – UGC NET Question

A longitudinal study follows the same individuals or groups over time, collecting data at multiple intervals to observe changes, trends or developmental patterns. This design is especially useful in educational and psychological research where growth, learning trajectories or long-term effects of interventions are of interest. By keeping the sample constant, researchers can attribute changes more directly to time or experiences rather than to differences between people. Hence, a design with repeated study of the same participants over an extended period is correctly called longitudinal.

Option A:
Cross-sectional studies, by contrast, collect data from different individuals at a single point in time, providing only a snapshot of conditions. They cannot directly trace changes within the same individuals, which is the central feature of longitudinal research described in the stem. Therefore, cross-sectional is not the correct option here.

Option B:
Experimental designs manipulate an independent variable and typically compare groups under different conditions; they may or may not involve repeated measures. While an experiment can be longitudinal if it extends over time, the term experimental alone does not emphasise the repeated observation of the same group across a long period, which is the key element in the question.

Option C:
Longitudinal research can take various forms, such as panel studies or cohort studies, but all share the feature of repeated measurement on the same participants. This allows researchers to analyse trajectories, stability and change at the individual level. Because the stem focuses on studying the same group over time, longitudinal is the accurate completion.

Option D:
Ex post facto research examines existing groups after an effect has occurred, often at a single time point, without manipulating variables. It does not necessarily involve repeated observation of the same participants over an extended period. Consequently, ex post facto study is not the right answer here.