Item-Validity Analysis of the SED-S in a Multicentre Study of Adults with Intellectual Disabilities

Background: Valid and reliable instruments for measuring emotional development are critical for a proper diagnostic assignment in individuals with intellectual disabilities. This exploratory study examined the psychometric properties of the items on the Scale of Emotional Development--Short (SED-S). Method: The sample included 612 adults with intellectual disabilities (M[subscript age = 37.35, SD[subscript age] = 13.27; 59.8% males). Item validity analysis comprising sensitivity and specificity rates and discriminatory power were determined. Results: The relative mean frequency of 'yes' answers to all 200 items was 29.5%. The mean sensitivity rate was 67.5% and the mean specificity rate was 79.3%. Most items (85.0%) showed good discriminatory power with the adjacent stage(s), especially between SED-1, SED-2, SED-3 and SED-4. Particularly in SED-4 some items showed weaknesses in the differentiation between these stages. Discussion: This study adds to previous validation studies by showing that most SED-S items have psychometrically sound properties.