Problem of item overlap between the Psychopathy Screening Device and attention deficit hyperactivity disorder, oppositional defiant disorder, and conduct disorder rating scales

Content validity requires a clear definition of the construct of interest a nd the delineation of the construct from similar constructs. Content validi ty also requires that the items be representative of the construct as well as specific to the construct. An examination of the items on the Psychopath y Screening Device (PSD), a parent- and teacher-rating scale of childhood p sychopathy, indicates significant overlap with the symptoms and associated features of attention deficit hyperactivity disorder (ADHD), oppositional d efiant disorder (ODD), and conduct disorder (CD). The failure of the PSD to have unique items results in poor discriminant validity with ADHD, ODD, an d CD rating scales. More careful attention to content validation guidelines is required to develop a more useful measure of childhood psychopathy.