panelstudies

Panel studies are longitudinal research designs in which the same units—people, households, firms, or other entities—are surveyed or observed at multiple points in time. The resulting panel data combine cross-sectional and temporal variation and are used to analyze change, development, and causal relationships.

Panels vary by composition and retention. A balanced panel tracks a fixed set of units across waves; unbalanced panels permit attrition and new entrants. Some designs are rotating or refreshed to maintain sample size. Data are collected at regular intervals (annual, biennial, etc.), and researchers may harmonize measures across waves.

Analytical advantages include ability to control for time-invariant unobserved heterogeneity through fixed-effects models, to study dynamics with lagged variables, and to use methods like difference-in-differences or dynamic panel techniques. Limitations include attrition and panel conditioning, panel mortality, nonresponse bias, measurement error, and higher costs. Missing data require treatment and weights.

Prominent panel studies include the U.S. Panel Study of Income Dynamics (PSID) and the German Socio-Economic Panel (SOEP); the UK's British Household Panel Survey (BHPS) and its successor Understanding Society; and European panels such as the European Community Household Panel (ECHP) and other longitudinal surveys.

Data quality and documentation are crucial, including sampling designs, response rates, weight construction, and variable harmonization. Ethical considerations include privacy, informed consent, and data access controls.