Data analysis
Depression
REGRESSION
Using SPSS version 27, we performed a series of linear mixed effects regression analyses at each post-treatment time point of the relationship between Group and each outcome measure (DASS-21 Depression, DASS-21 Stress, PANAS, PSI-4, AAQ-II, VLQ, CFQ, BMPS, BFDS, FAD, SDQ). As fixed effects, we entered Group (Treatment/Waitlist), Time (two levels: Baseline and Time 2 or 3), and Group × Time interaction into the model. The interaction directly tested whether Treatment and Waitlist groups showed a different pattern of change in outcome measures at the different study time points. As random effects, we included an intercept for subjects to account for repeated measurements. Mixed effects models accommodate for missing values using the maximum likelihood method, and therefore, this analysis included all randomized participants (Cohen’s Differences between the Treatment and Waitlist groups in their goal attainment (i.e. goal achieved/not achieved) were tested using Pearson chi-square analyses. Missing goal attainment values were imputed in SPSS using multiple imputation, including all demographic variables, baseline scores, and variables in the analysis as predictors. Chi-square values from 10 imputed datasets were pooled in R using the micombine.chisquare function from miceadds (Two analyses included treatment completers only from the Treatment group (