To measure teacher-reported oppositional behavior in the classroom during school age, we used the DSM-oriented Oppositional Defiant Problems scale from the Teacher Report Form (TRF; Achenbach & Rescorla, 2001) version of the CBCL. The TRF is a well-validated measure of child problem behavior and was administered to the primary teacher of study participants at age 7.5. Internal consistency for the 5-item scale was .90.
