On the basis of the standard deviation (31.21) and alpha values obtained in the present study, a change of more than 15.95 from pre- to posttreatment or follow-up was considered reliable (Jacobson & Truax, 1991). There were no significant differences in reliable change rates at posttreatment. At follow-up, 19.7% of the TAU participants had improved and 15.2% deteriorated, as compared to 30.9% improved and 2.9% having deteriorated in the ACT condition, a significant difference in improvement (Fisher’s exact, p = .04) and deterioration (Fisher’s exact, p = .026).
