Parent ratings of the ADHD items of the disruptive behavior rating scale: Analyses of their IRT properties based on the generalized partial credit model

Generalized partial credit model (GPCM), which is based on item response theory (IRT), was used to evaluate the psychometric properties for the DSM-IV inattention (IA) and hyperactivity/impulsivity (HI) items for boys and girls. To accomplish this, parents completed the disruptive behavior rating scale (DBRS; Barkley & Murphy, 1998) for 403 boys and 380 girls, between 6 and 11 years of age. The results for the slope parameters showed that for both groups, all items were generally good for discriminating their respective latent traits. The results for the location parameters in both groups showed that endorsement of higher ratings of all the items in the DBRS would require a considerable amount of the relevant latent traits (IA or HI) to be present. Thus there was good support for the psychometric properties for the ADHD items in the DBRS. These findings extend existing data on the psychometric properties of ADHD rating scales.