Young people's lived experience expertise: Insights from the DigiCAT project to develop a counterfactual analysis tool for mental health data

Abstract Background Lived experience (LE) expertise is increasingly recognised as a vital component in mental health research. In our project to develop a digital tool for counterfactual analysis (DigiCAT), with an emphasis on researching active ingredients for adolescent mental health, we incorporated LE expertise across the lifecycle of tool development and dissemination. Methods We consulted young person advisory groups (YPAGs; aged 11–18 years old) across three project phases—Discovery, Prototyping, and Dissemination—using structured discussions, ranking exercises, and iterative feedback loops to shape research priorities, tool design and user tutorials, and dissemination strategies of the tool. Results The YPAGs advised on active ingredients and features of such ingredients that existing research has not taken into account. Examples include young person advisory group (YPAG) suggestions to prioritise research in social media, peer relationships, and teacher‐student relationships. We incorporated these suggestions as illustrative examples in our tutorial paper introducing DigiCAT to our target audience, to demonstrate how insights from YPAGs can inform the use of the tool in research, by guiding areas of study. These areas were also prioritised in our own empirical analyses using the tool. Additionally, the YPAG contributed practical guidance on how to effectively involve youth LE experts in both research and digital tool development processes. Conclusions The integration of LE expertise fundamentally shaped the development of our tutorial paper, influencing both its instructional components and its broader discussion of applications in mental health research. This project highlights the value of embedding LE perspectives into research guidance for software use, offering a model for future mental health and digital innovation initiatives.