Moderated Mediation Analyses
As a first step, LMMs were used to investigate intervention effects on longitudinal changes in the weekly measured variables of acceptance, empathic listening, empathic distress, mindfulness, and interoceptive awareness. For mindfulness and interoceptive awareness, mean scores were computed across the corresponding items. In the first week of the first intervention phase, data on empathic listening were missing for 66.5% (145/218) of the participants because of technical issues with the smartphone app. Therefore, analyses of longitudinal changes in empathic listening only included weeks 2 to 10. Participants with data on <3 measurement occasions were excluded from longitudinal change and mediation analyses (3/218, 1.4%). As dependent measures were only assessed in the intervention groups, the main models included only the socioemotional and mindfulness-based groups, with fixed effects for intervention group, time, and an interaction term of group and time and with mindfulness-based defined as the reference group. The models included random intercepts and slopes. The separate random-intercept models for the waitlist socioemotional group in the second intervention phase included a fixed effect of week. The estimated individual slope coefficients were extracted from the LMMs for further mediation analyses.In the mediation analyses, for changes from preintervention assessment to postintervention assessment 1 in each self-report and behavioral outcome measure of compassion for the self and others and empathy (