Longitudinal data, panel data: methods and analysis

Longitudinal studies allow the investigation of dynamic processes of media use and effects. The most frequently used longitudinal design in media psychological research is the panel design. Panel studies are typically survey based and assess the same behaviors, attitudes, or emotions at least twice among the same participants. Panel studies are time intensive and expensive. Potential problems such as panel mortality, consistency of measures over time, and panel conditioning effects need to be considered when designing longitudinal studies. Although longitudinal studies are frequently used to assess causal relationships, researchers need to be aware of the limitations in drawing causal claims from panel data. There are a variety of statistical methods available for examining longitudinal data. When choosing the best method, researchers need to take into account the nested structure of the data, as well as the theoretical question they want to answer. Cross-lagged panel models and latent growth models are frequently used statistical methods for longitudinal data in media effects research.