Chapter 8: Single and Multilevel Models for Counts

Nearly all disciplines rely on count data to capture the frequency of specific events or occurrences of behaviors. In education settings, counts can be used to assess how often individual children in special education classrooms may be disruptive or may show prosocial behaviors. Other examples include counts of the number of words recalled during auditory exams, the number of volunteer experiences completed by high-school juniors and seniors, the number of times the "help" feature is accessed during an online algebra tutorial, or counts of violent crime events across different school zones or districts. Counts are common outcomes for intervention studies designed to reduce (or increase) the occurrence of particular events or behaviors, but analyzing such data brings unique challenges.