Table 1 Study research questions

Face validity and practicality

1. Is the CHU9D simple to understand and complete?

CHU9D should be well understood and easily completed by participants.

Reliability

2. What is the internal consistency of the CHU9D?

Instrument should have acceptable to excellent internal consistency indicating the items are tapping into the same general construct (health-related quality of life).

Convergent validity

3. How do items and scores on the CHU9D correlate with items and scores from the Strengths and Difficulties Questionnaire (SDQ), a well-established and widely used routine outcome measure in child and adolescent mental health?

Items and scores on the CHU9D should demonstrate predictable and moderate to high correlations with items and scores on the SDQ, indicating they are tapping into the same broad construct (psychosocial functioning).

4. Can the CHU9D discriminate between children in the clinical and non-clinical range on the SDQ?

Scores on the CHU9D should be able to discriminate between children at different mental health symptom severity levels.

Validity of utility weights

5. How do the utility weights from this child and adolescent mental health sample compare against utility weights obtained from other child and adolescent mental health samples?

The utility weights that the CHU9D generates for this mental health population should reflect utility weights obtained in other similar mental health populations.