Understanding source effects in ADHD rating scales: reply to DuPaul (2003).

G. J. DuPaul (2003) offered two suggestions for additional research to understand the strong source effects reported by R. Gomez, G. L. Burns, J. A. Walsh, and M. A. de Moura (2003) in attention-deficit/hyperactivity disorder (ADHD) rating scales. The first suggestion was to determine whether the source effects represent mostly bias or accuracy. The second suggestion was to minimize source effects through the development of better ADHD rating scales. Because source effects can represent bias or accuracy, it is important to minimize the bias aspect through content validation procedures prior to attempts to determine whether source effects better reflect bias or accuracy. This comment offers various suggestions to reduce the bias in ADHD rating scales.