Study 1
Baker-Henningham and colleagues (2012) conducted a cluster randomized controlled trial of 24 community preschools in the inner-city areas of Kingston, Jamaica, during the 2009–2010 school year. The preschools were randomly assigned to receive the Incredible Years–Teacher Classroom Management (IY–TCM) training (n = 12) or to a control group (n = 12). The intervention group schools included 37 classrooms and 959 children, while the control group schools included 36 classrooms and 955 children.
Three children from each class with the highest levels of teacher-reported conduct problems were selected for inclusion. The total sample comprised 225 children ages 3 to 6 years. There were 113 children in the intervention group and 112 children in the control group. The average age of children in the intervention group was 4.2 years, and 67 percent were boys. The average age of the control group was also 4.2 years, and 71 percent were boys. No statistically significant differences were found between groups on any baseline characteristics.
Child outcomes were measured using observations of in-class child behavior, as well as teacher and parent reports of child behavior. For the observations of child behavior, within each class, three children were observed for 5 minutes each on a rotational basis for a total of 15 minutes per day, per child, over 4 days. This resulted in a total of 1 hour of observation. Event recording was used to count aggressive/destructive behaviors (such as hitting or pushing) and friendship skills (such as sharing) and was expressed as a frequency per hour. For teacher- and parent-reported child behavior, the Sutter-Eyberg Student Behavior Inventory (SESBI) was used to measure child conduct problems; Connor’s Global Index was used to measure hyperactivity and attention difficulties; the Strengths and Difficulties Questionnaire (SDQ) was used to measure behavior difficulties and prosocial skills; and the Preschool and Kindergarten Behavior Scale (PKBS) was used to measure child social skills. Data was collected at baseline (October–November 2009) and at postintervention (May–June 2010).
The impact of the IY–TCM program on continuous outcome measures was examined using multilevel multiple regression models. An intent-to-treat analysis was conducted using baseline scores for missing data at postintervention. No subgroup analyses were conducted.
Study 2
Hutchings and colleagues (2013) used a single-blind, stratified randomized controlled trial of six intervention and six control classrooms, in both rural and urban areas, in the county of Gwynedd in northwest Wales. The schools were randomly assigned to the Incredible Years–Teacher Classroom Management (IY–TCM) training or to a control group.
Twelve classrooms and a total of 16 teachers participated. Teachers in the study were all women with an average age of 34 years. The study sample consisted of a total of 107 children between the ages of 3 and 7 years. There was a total of 53 children in the intervention group and 54 children in the control group. The average age of children in the intervention group was 5 years, and 55 percent were girls. The average age of the control group was 5 years, and 55 percent were boys. All participating children across study samples were white. No significant differences were found between groups on any baseline characteristics.
The Teacher Version of the Strengths and Difficulties Questionnaire (TSDQ) was used to assess hyperactivity, peer problems, emotional problems, conduct problems, and pro-sociality. The Teacher-Pupil Observation Toll (TPOT) was used to measure negative traits such as behavioral, social, and emotional problems and positive traits such as pro-sociality. To measure fidelity, three tools were used: 1) The Teacher Satisfaction Questionnaire, 2) Incredible Years teacher workshop evaluations, and 3) the teacher workshop checklist.
To measure the effect of the IY–TCM intervention on child and teacher behavior, a hierarchal linear modeling (HLM) analysis was used. No subgroup analysis was conducted.