School-based physical activity support among Chinese adolescents: development and initial psychometric evaluation of a five-domain student-report scale

Abstract Background Schools shape adolescents’ opportunities, social experiences and institutional conditions for physical activity, but existing measures often combine policy, environment and lived experience into broad scores. This study developed and initially evaluated the 38-item School-Based Physical Activity Support Scale–Student Report (SBPASS-SR38), which distinguishes curricular, extracurricular activity, peer, cultural and institutional support. Methods Three sequential studies were conducted in China. Study 1 used review by five experts and cognitive interviews with nine adolescents (18 item-focused records) to evaluate content and response processes. A version audit restricted all analyses to 38 items with identical wording across study materials. Study 2 included 706 adolescents from eight schools and used item analysis, parallel analysis and polychoric exploratory factor analysis. Study 3 included 724 adolescents from six independent schools; 718 complete cases from 30 classes were used to compare seven class-cluster-robust ordinal models. Reliability, 14-day stability in 178 students and correlations with reports from 19 physical education teachers covering 30 classes were also examined. Results Scale-level content validity indices ranged from 0.953 to 0.989, and Study 2 recovered the proposed five factors. In Study 3, correlated five-factor confirmatory factor analysis fitted well (comparative fit index [CFI] = 0.957; root mean square error of approximation [RMSEA] = 0.018; standardised root mean square residual [SRMR] = 0.042), and five-factor target exploratory structural equation modelling fitted better (CFI = 0.983; RMSEA = 0.012; SRMR = 0.026). Second-order and bifactor confirmatory models did not converge. Bifactor exploratory structural equation modelling fitted slightly better, but the general factor was concentrated in extracurricular and peer items (omega hierarchical = 0.484; explained common variance = 0.449). Subscale omega ranged from 0.667 to 0.912 and absolute-agreement intraclass correlations from 0.677 to 0.880. All five means changed over 14 days, and no student–teacher correlation was statistically significant. Conclusions Initial evidence supports five student-reported support domains, but not a total score or interchangeability of student and teacher reports. The SBPASS-SR38 may support school-based public health research and programme evaluation after further testing of subgroup invariance, predictive validity and intervention sensitivity. Clinical trial registration Clinical trial number: not applicable.