A '''longitudinal study''' is a study that involves the repeated observation or examination of the same set of subjects over time with respect to one or more study variables, particularly in medical research where the subjects are living beings. A longitudinal study is often desired because it follows changes in the same people. In contrast, a cross-sectional study compares results across different people, which can introduce undesired variables to distort the results.
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A '''longitudinal study''' is a study that involves the repeated observation or examination of the same set of subjects over time with respect to one or more study [[variables]], particularly in [[medical]] research where the subjects are living beings. A longitudinal study is often desired because it follows changes in the same people. In contrast, a [[cross-sectional study]] compares results across different people, which can introduce undesired variables to distort the results.