Parental ratings of overactivity are unrelated to teachers' ratings of overactivity or to laboratory measures of inattention. Teachers' ratings of overactivity correlate strongly with teachers' ratings of inattention as well as to laboratory measures of inattention. Teachers' ratings of inattention, however, are unrelated to laboratory measures of inattention when IQ is controlled. There are considerable definitional problems relating to the symptoms of hyperactivity and inattention, making it difficult create a behavioral definition of the psychiatric syndrome of attention deficit disorder.
Shaffer, David and Schonfeld, Irvin Sam, "Critical note on the usefulness of attention deficit as a clinical syndrome" (1984). CUNY Academic Works.