Final answer:
A longitudinal study where the same sample is tracked over time is referred to as a panel study, which is closely related to a cohort study but with a slightly different focus.
Step-by-step explanation:
A type of longitudinal study in which the same sample of respondents is tracked over a long period of time is known as: a. A panel study. Longitudinal research typically involves collecting data from the same individuals repeatedly over an extended period of time. In the realm of social studies and observational research, a panel study is closely related to a cohort study; however, cohort studies generally focus on observing a group with a shared characteristic and may not always recontact the same individuals. In contrast to cross-sectional and case-control studies which are more limited in tracking changes over time, longitudinal and panel studies are ideal for understanding the development and evolution of certain phenomena.