This document discusses longitudinal survey research design. It describes longitudinal research as involving repeated observations of the same variables over time. The document outlines the main types of longitudinal research: trend studies, which examine changes within a population over time; cohort studies, which identify a subgroup sharing a characteristic to study over time; and panel studies, which examine the same individuals repeatedly. Strengths are identified as the ability to establish sequences of events and trace development. Drawbacks include high costs and risk of participants dropping out.