Determinants of physical activities in settings (DE-PASS): Approach for selecting the core measures for determinants of physical activity behaviours in 9-12 old children.

In large transdisciplinary research teams finding the balance between using the most appropriate and needed measures for data collection and minimising participant burden is often a significant challenge. This paper aims to describe the development process for selecting a set of determinants of physical activity behaviours in 9-12 years old children. An internal small group ( = 8) worked iteratively with an external large group of experts and stakeholders ( = 30-50) in three steps: 1) External input - Identification through expert opinion; 2) Internal input - Identification and selection via a systematized approach; 3) External validation of the selected measures. During these steps, 113 measures were first identified, then scored, sorted, and selected using evidence-building practices such as systematic literature reviews, peer-review, and consensus discussions. Eighteen measures were agreed and included in the core measures toolkit (child and caregiver questionnaires). In conclusion, pragmatism, implementation concerns, and the experts' experience were key in this process. This process may be considered as a reference to others involved in the challenge of selecting measures in their research.