Panel Studies

Panel studies, sometimes also referred to as prospective studies, are longitudinal surveys that collect data from the same units of analysis on multiple occasions. In psychology and the social sciences, the units are usually people, but they could also be households, firms, schools, or other entities. Each individual survey in a panel study is [Page 1571]called a wave, and in some rare cases, a sweep. Panel studies are distinct from (a) pure cross-sectional surveys that collect information only once about that precise point in time, (b) trend data that collect data on the same topics at different points in (historic) time, always using new samples, and (c) retrospective life-course studies that collect information on past events, statuses, and their durations (e.g., family, school, or employment histories). Under certain circumstances, however, panel data can be analyzed in the same way as trend data. Moreover, panel studies often collect additional retrospective data (usually in one of the first waves) as well as data on events that take place between successive waves to obtain detailed information on careers (e.g., reproductive, employment, or labor market careers). Although well-designed experiments with at least one pre- and at least one posttreatment measure fulfill all of the requirements of a panel study, they are not normally referred to as such. There are some exceptions, however, such as the HighScope Perry Preschool Study.

This entry describes the benefits of panel data for describing and analyzing life-span development and, in particular, for causal analysis of observational data. Panel studies are designed with specific considerations in mind, such as the need to keep sample units in the survey, maintain representativeness over time, and achieve an optimal interval between the successive survey waves. To illustrate the importance of these considerations in the context of a wide variety of available survey designs, examples from major panel studies are discussed. Finally, the types of training and methods needed for handling and analyzing panel data are outlined.