Development of the Quality of Life in Youth Services Scale (QOLYSS): Content-Related Validity Evidence Based on Adolescents’ and Expert Reviewers’ Perspectives

Despite increased interest in the quality of life of younger populations, the quality of life of youngsters in vulnerable situations such as those in youth services remains under-researched. To gain insight into critical ingredients for understanding and enhancing the lives of these youngsters, appropriate assessment tools are needed. This study focuses on providing content-related validity evidence for the new Quality of Life in Youth Services Scale (QOLYSS) for adolescents in youth services. A sequential approach to item generation, refinement, and evaluation is presented. The initial item bank is devised by means of a thorough literature search and evaluated against findings from qualitative research among adolescents in youth services. In addition, a three-round international expert panel (N = 5) is convened to align identified items to the adopted quality of life framework, and to provide evidence on domain representation and relevance. Last, input is collected from adolescents in youth services themselves. More specifically, 20 group discussions and 13 individual interview sessions are organized to support 21 adolescents in critically assessing the content of the item bank on level of relevance, clarity, and coverage. The expert panel resulted in a provisional scale of 262 unique items that, based on adolescents’ input, is further reduced to a set of 88 items. Adolescents omitted items because of divergent reasons (e.g., content-overlap, self-evident character of the items, level of irrelevance). Explanatory qualitative information on the item selection process is provided. This study provides a detailed understanding of the content-related validity evidence of a new multidimensional quality of life scale. Moreover, it highlights the importance of acknowledging youngsters as critical partner in quality of life research and assessment.