Tebes, Jacob Kraemer; Snow, David L.; Ayers, Tim S.; … - In: Evaluation Review 20 (1996) 4, pp. 470-484
This study investigates the relationship of panel accretion to panel attrition and examines its impact on threats to external validity in adolescent substance use research. Panel accretion involves the addition of new participants to a panel design after initial baseline data has been obtained....