The determination of what constitutes a ‘meaningful change’ on a health outcome measure remains controversial in both methodological and applied research. Motivated by the question of how to understand the efficacy and effectiveness of interventions or the natural history of conditions better [
1,
2], the concept builds on the widely held belief that statistical significance in itself is not sufficient to establish a treatment benefit [
3,
4]. Since health-related quality of life (HRQL) research should reflect patients' perceptions and evaluations, the topic is of immense theoretical, statistical, and practical relevance. It was therefore timely to offer a space to present discussions, methods, and questions related to this topic, even as new methods and interpretive standards emerge. …