Factorial validity and group invariance of the Portuguese short version of the Social Physique Anxiety Scale in adolescents

Social physique anxiety (SPA) has been associated with a range of psychosocial and health-related variables, thus it can be considered is an indicator of social-psychological adjustment. The purpose of this paper is to determine factorial validity and group invariance of Motl and Conroy (2000) translated 7-item SPA among Portuguese adolescents. A nationally representative sample of 3330 8th and 10th grade students (15.07  1.34 years old; 47.5% males and 52.5% females) answered a survey as a part of a larger collaborative cross-national survey, the Health Behaviour in School-Aged Children (HBSC) 2006 study. Exploratory and confirmatory factor analyses resulted on a uni-dimensional factor structure of 6 items [Satorra-Bentler c2 = 30.85, df = 8, p<.01; CFI = .996; NNFI = .992; RMSEA = .038 (90% C.I.: .024 - .052); SRMR = .010]. Further analises, confirmed configurational (all CFI and RMSEA > .99) and metric invariances (CFI difference between restricted and unrestricted models were lower than .01 for all groups) across gender, grade level, diet beliefs, physical activity, perception of body, and BMI. The present version can be used confidently by researchers in analysing and interpreting scores of SPA across a variety of samples in Portuguese adolescents, and that this instrument can be used in cross-cultural research.