Statistical, Practical, Clinical, and Personal Significance: Definitions and Applications in Speech-Language Pathology

Purpose: To discuss constructs and methods related to assessing the magnitude and the meaning of clinical outcomes, with a focus on applications in speech-language pathology. Method: Professionals in medicine, allied health, psychology, education, and many other fields have long been concerned with issues referred to variously as practical significance, clinical significance, social validity, patient satisfaction, treatment effectiveness, or the meaningfulness or importance of beyond-clinic or real-world treatment outcomes. Existing literature addressing these issues from multiple disciplines was reviewed and synthesized. Conclusions: Practical significance, an adjunct to statistical significance, refers to the magnitude of a change or a difference between groups. The appropriate existing term for the interpretation of treatment outcomes, or the attribution of meaning or value to treatment outcomes, is clinical significance. To further distinguish between important constructs, the authors suggest incorporating as definitive the existing notion that clinical significance may refer to measures selected or interpreted by professionals or with respect to groups of clients. The term personal significance is introduced to refer to goals, variables, measures, and changes that are of demonstrated value to individual clients.