Multilevel Modeling and Practice-Based Research

Abstract

PURPOSE The health care system in the United States is inherently hierarchical. Patients are “nested” within physicians who in turn are “nested” within practices. Much of the research data gathered in practice-based research networks (PBRNs) also have similar patterns of nesting (clustering). When research data are nested, statistical approaches to the data must account for the multilevel nature of the data or risk errors in interpretation. We illustrate the concept of multilevel structure and provide examples with implications for practice-based research.