Item response theory (IRT) models are the main psychometric approach for the development, evaluation, and refinement of multi-item instruments and scaling of latent traits, whereas multilevel models are the primary statistical method when considering the dependence between person responses when primary units (e.g., students) are nested within…

Early adolescents vary in their susceptibility to peer influence on delinquency. However, it is still less clear which factors explain this variation and how these factors relate to each other. In this study, 10 factors that may moderate peer influence were investigated. A sample of 868 participants was followed across six occasions from seventh…

Applied early adolescent researchers often sample students (Level 1) from within classrooms (Level 2) that are nested within schools (Level 3), resulting in data that requires multilevel modeling analysis to avoid Type 1 errors. Although several articles have been published to assist researchers with analyzing sample data nested at two levels, few…