Statistical analyses
SECONDARY
Data entry and statistical analysis were performed using SPSS 22.0. The success of the randomization process was first tested by running a one-way ANOVA to test for differences in pre-measure across the three groups (ACT group, REBT group, and control group). Then, analysis of covariance and Bonferroni post hoc comparisons were applied to determine the differences in post-measure across the three groups. Effect size was reported as ηSimple mediation models were performed with psychological flexibility or cognitive fusion as the mediator, group condition (ACT/REBT vs. control) as the independent variable, baseline values of the outcome and mediator as covariates, and post-intervention values of the primary or secondary variable as the dependent variable. Mediation was examined with a bootstrapping method and the PROCESS macro for SPSS (