Assessors and Therapists
The assessors and therapists (n=22) were registered provisional and generalist psychologists who were undertaking a postgraduate clinical placement within a community mental health service. Each assessor and therapist had undertaken coursework in clinical psychology, including psychological assessment and interventions, as well as completing a purposively developed 14-hour, 5-module web-based training program covering DMH interventions (specifically video chat technology), diagnostic assessments, qualitative interviewing techniques, and transdiagnostic CBT principles that underpin the Life Flex program. The training program comprised a 40-item multiple-choice competency assessment on which therapists were required to obtain a minimum score of 80%.All assessors were required to demonstrate competency in diagnostic assessments before administration. Both assessors and therapists received daily training and supervision throughout the trial from the first author, an experienced clinical psychologist. Assessment and therapist sessions were audio or video recorded (with participant permission) so that random checking (20% of the total) could be completed to ensure fidelity to administration, enable agreement and interrater reliability of diagnoses, and ensure that fidelity to the therapist’s role (low or high intensity) was maintained. At least one treatment session was reviewed for each therapist. An adapted version of the Internet-Delivered Cognitive Behavior Therapy–Therapist Rating Scale [