Brief report: testing measurement invariance and differences in self-concept between adolescents with and without physical illness or developmental disability.

The aim of this study was to test for measurement invariance and examine differences in global self-concept between adolescents with and without physical illness or developmental disability. The sample consisted of adolescents 10-19 years who participated in the Canadian National Longitudinal Survey of Children and Youth (N=8491). Multiple group confirmatory factor analysis was used to test for measurement invariance. Twenty-three percent (n=1966) of participants had a physical illness or developmental disability. Support was found for strict measurement invariance between groups suggesting adolescents in both groups perceived items similarly, indicating that comparisons between adolescents with and without physical illness or developmental disability are meaningful. Controlling for several sociodemographic characteristics, evidence suggested that self-concept is lower in adolescents with physical illness or developmental disability, β=-0.24, p=0.0005, compared to their healthy peers. Future work should attempt to understand the processes leading to compromised self-concept in adolescents with physical illness or developmental disability.