RCTs of complex interventions in mental health care: what works for whom?

„Conventional“ intent-to-treat-analysis merely answers the question „Does it work?“, while process evaluation yields insights into „For whom does it work (best)?“ and „What works?“ Thus, process analysis aims at elucidating why an intervention did or did not work and which subgroups of patients in which settings did or did not benefit from it. Sound analysis of moderators and/or mediators of treatment effect is crucial to inform future applications of results of randomized controlled trials. It is especially important to answer the question whether an intervention was truly ineffective or just poorly delivered.…