Longitudinal design is defined as a special kind of systematic observation, implemented by correlational researchers, which involves the tasks of obtaining measures of variables of interest in multiple waves over time.
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Longitudinal design is one of the known systematic observation pattern followed by the correlational researchers in which a subject of experiment is observed for a significantly long span.
The three types of longitudinal design are: panel study, cohort study and retrospective study. The complete design involves the multiple set of observations over a variable or subject. Longitudinal design is often used in clinical psychology to study rapid fluctuations in the behaviour.
