Study 1
Liber and colleagues (2013) studied the intervention effects of a cognitive behavioral treatment (CBT) program, using a school-based, randomized controlled trial method. The Keep Cool...Start at School program was administered during 3 consecutive school years at 17 different middle schools in low-to-middle socioeconomic status (SES) urban areas in the Netherlands. Students were randomly placed into the intervention or waitlist control group based on grade level; both groups comprised participants from grades 5–8. To be eligible for inclusion, students were screened by two teachers independently using the List Global Screening (LSG), a 6-item questionnaire that seeks to identify children that display symptoms of antisocial behavior. The scores from each teacher were combined to identify at-risk students, and these students were then selected to participate in the study. Of the students selected to participate (n = 280), parental consent was required and obtained for 224 students. The sample was further confined to include only students whose IQ was greater than 85, resulting in a final sample of 171 students. Students with an IQ below 85 were excluded from the study sample, as they were not expected to understand the cognitive content of the training administered. The majority of the students were male (n = 136), low SES (n = 96), and self-identified as non-Western immigrants (n = 109), including those who identified as Turkish, Moroccan, and Afghan.
Students were randomly assigned to the intervention group (n = 70) or waitlist control group (n = 103).Students were assessed in time waves, ranging from wave 1(T1) to wave 4(T3). T1 included the screening, assessment, and selection to participate in the study, as described above. The intervention group received the treatment between time periods T2 and T3. The waitlist control group did not receive the treatment during this time. Data on pre–post changes between the intervention and waitlist control groups was collected at T3 (1 to 2 weeks after the intervention concluded).
The study focused on four outcomes: (1) conduct disorder; (2) oppositional defiant disorder; (3) externalization of behaviors; and (4) parent-report measurements. Four specific scales were used to collect data on the outcomes. The Teacher Report Form (TRF), a 113-item Likert scale used to assess behavior problems, focused on conduct disorder and oppositional defiant disorder in students. The Disruptive Behavior Disorders Rating Scale (DBDRS) assessed symptoms on a 4-point Likert scale, which focused on conduct disorder and oppositional defiant disorder. The Peer Measurement of Internalizing and Externalizing Behavior (PMIEB), a 22-item peer-nomination scale evaluating psychopathology in children, was used to analyze external behavior and body language. Finally, the Strengths and Difficulties Questionnaire (SDQ), which focuses on the parent’s perception of strengths and difficulties their children express, was measured through a rating of 25 items on a 3-point Likert scale. Parents rated children’s attributes such as emotional symptoms, conduct problems, peer relationships, and inattention problems (Goodman, 2001). No subgroup analyses were conducted.