ABSTRACT
In general there are three groups of statistics that have been used to express the consequences of psychotherapy for patients: statistical significance of within and between group differences, effect size, and clinical significance. Jacobson Truax introduced a first statistical method to assess clinically significant change. A common and comparable database of studies with rates of clinically meaningful change determined using the same parameters and methods will bring added consistency and interpretive meaning for clinicians, researchers, and clients who consume the psychotherapy research literature. Psychotherapy research has been historically undervalued by clinicians but can have far greater impact on client well-being and clinical practice through the use of clinical significance methods and increased attention to changes that occur in the life functioning of individual clients. One with a chronic illness might move from a severe to a moderate range and thus meet the definition of clinically meaningful change.
