A psychometric evaluation of the ARC-INICO Self-Determination Scale for adolescents with intellectual disabilities

The independence to decide and act as the causal agent in one's life are unchanging demands by empowerment movements focused on people with disabilities and by people with disabilities themselves. International efforts have been devoted to defining the concept of self-determination, analyzing its importance and relationship with the quality of life of people with disabilities and creating evaluation and promotion materials based on empirical evidences. The aim of this study is to present the process for developing and validating a new self-determination evaluation instrument for young people with intellectual disabilities: the ARC-INICO Scale. The sample for validating the Scale comprised 279 young people with intellectual disabilities, limited intellectual capacities and learning difficulties. The participants were aged between 11 and 19 years (M = 15.59, SD = 1.89). The results indicate that both the Scale and the four sections into which it is divided were reliable. The confirmatory factor analysis shows proof of validity based on the internal structure of the Scale, and confirms the correct fit of the proposed hierarchical structure. Practical implications and future directions of research are also discussed.