Table 1.

Method of child selection for analyses in multiple-child families

If there are two or more eligible children in a family, all children will be included in the study, and data will be collected on all of them. However, only one child will be selected to be included in the final analyses. This selection will use the following rules, which: (1) prioritise inclusion of children who screen positive and are, therefore, included in the target population and (2) ensure that, in the screening and intervention arm, the child who has been chosen (by their parent) to be the ‘target’ child for receiving the intervention is included in the analyses (in the target and total populations). • If only one child in the family screens positive on the baseline parent-report iCATS-2, this child will be included in the analyses (in the target population). • If more than one child in the family screens positive on the baseline parent-report iCATS-2, and the children are in the usual school practice arm, the child with the lowest study ID number out of those who screen positive will be included in the analyses (in the target population). • If more than one child in the family screens positive on the baseline parent-report iCATS-2, and the children are in the screening and intervention arm, the child who the parent has chosen to be the ‘target’ child for receiving the intervention, out of those who screen positive, will be included in the analyses (in the target population). If the parent does not choose any child to receive the intervention, the child with the lowest study ID number will be included in the analyses • If none of the children in the family screen positive on the baseline parent-report iCATS-2, and the children are in the screening and intervention arm, the child who the parent has chosen to be the ‘target’ child for receiving the intervention will be included in the analyses (in the total population). If the parent does not choose any child to receive the intervention, the child with the lowest study ID number will be included in the analyses. • If none of the children in the family screen positive on the baseline parent-report iCATS-2, and the children are in the usual school practice arm, the child with the lowest study ID number out of those who screen positive will be included in the analyses (in the total population).