Treatment Integrity in Intervention Research: Models, Measures, and Future Directions

Treatment integrity (TI; also known as fidelity of implementation, treatment fidelity, and procedural reliability) refers to the degree to which an intervention is implemented as intended. TI data provides evidence of the internal validity of a study; without TI data, one cannot attribute observed effects to an intervention or distinguish whether interventions that fail do so because of problems with the intervention, its delivery, or both. Unfortunately, the field of intervention research has seen limited progress in the assessment and reporting of TI over time. This chapter describes the development of models of TI across fields, options for measuring TI, and important issues yet to be resolved.