Item Response Theory Analyses of Adult Self-Ratings of the ADHD Symptoms in the Current Symptoms Scale

The graded response model, which is based on item response theory, was used to evaluate the psychometric properties of adult self-ratings (N = 852) of the attention deficit/hyperactivity disorder inattention, hyperactivity, and impulsivity symptoms presented in the Current Symptoms Scale. This scale has four ordered response categories. The results for the discrimination parameters showed that all symptoms were generally good for discriminating their respective latent traits. For virtually all symptoms, their threshold values showed that they were especially good at representing the appropriate traits from around the mean trait level onward. The item information function values for most symptoms indicated reasonable reliability from approximately the mean trait level onward. All these findings are new and extend existing psychometric information for adult self-ratings of the attention deficit/hyperactivity disorder symptoms in the Current Symptoms Scale.