Many child and adolescent mental health services (CAMHS) have established routine outcome measurement systems at the service level . These often include broad measures of mental health symptoms, problems, and functioning rated by several informants, such as parents, teachers, and young people [2–4], or by clinicians [5–7]. These assessments require empirical evidence of their acceptable reliability, validity, feasibility, and sensitivity to change when used in routine outcome evaluations . In the absence of gold standard criteria, we can assess the validity of a measure by investigating its correspondence with comparable measures .
The Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) is an outcome measure rated by clinicians. It is a brief, quickly completed instrument that measures broad aspects of mental health problems and functional impairment. The HoNOSCA was established as a mandatory routine outcome measure of CAMHS in Australia , New Zealand , and Denmark , and has been widely used in the United Kingdom . Several studies have concluded that it is a valid, reliable, and change-sensitive measure [7, 14–19], and several studies have specifically examined the concurrent validity of HoNOSCA . The correlations between the HoNOSCA total score and other clinician-rated measures, such as the Children's Global Assessment Scale (r = -0.35  and r = -0.64 ), the Global Assessment of Psychosocial Disability (r = 0.46) , and the Paddington Complexity Scale (r = 0.46  and r = 0.62 ) have been medium to large. Clinicians make important contributions to mental health assessments, and they require information about their patients' behaviour and functioning from the patients themselves or from people who know them. There are several potential sources of systematic error in clinicians' judgments, which may include personal interests if their assessments are used for outcome evaluations. Because clinicians' judgments could be biased, we wanted to study the associations between clinicians' HoNOSCA ratings and the ratings by parents, teachers, and adolescent patients themselves.
Medium correlations have been reported between the HoNOSCA total score and the Strengths and Difficulties Questionnaire (SDQ) total difficulties score by parents (r = 0.38  and 0.40 ), by teachers (r = 0.46 ), and by young people (r = 0.36 ). Medium correlations were also found when the HoNOSCA total score was compared with the Achenbach System of Empirically Based Assessment (ASEBA) forms: the Child Behavior Checklist (CBCL; parent report) total problems (r = 0.39) and the Teacher's Report Form (TRF) total problems (r = 0.35) . However, further aspects of the concurrent validity of the HoNOSCA scales in routine clinical use must be investigated, to determine particularly whether they correlate, as expected, with similar scales of measures-rated by parents, teachers and adolescent patients.
The ASEBA is an integrated system of multi-informant assessment that is widely and routinely used in CAMHS. The 2001 versions of the CBCL and TRF are designed for subjects aged 6-18 years, and the Youth Self-Report (YSR) is designed for young people aged 11-18 years . The three ASEBA forms have similar questions and scales, which differ from the HoNOSCA scales. In the ASEBA forms, the respondents assess many, very specific behaviours, whereas in the HoNOSCA, the clinician rates the clinical severity of the symptoms and problems on 13 scales. Although there are considerable differences between the instruments in both their format and content, there are substantial similarities in the themes that are addressed.
Modest levels of inter-informant agreement (small correlations) in paired comparisons of the ratings of behavioural problems by parents, young people, and teachers are robust findings, and it has been concluded that "each type of informant typically contributes a considerable amount of variance not accounted for by the others" . As a consequence, multi-informant strategies are generally recommended as more valid than single-informant strategies for measuring mental health problems [4, 28]. As far as we know, only one previous study has compared HoNOSCA and ASEBA in a clinical setting. This study was published by Brann as a dissertation (PhD) in 2006 .
In the study presented here, we first investigated correlations between presumed corresponding scales from the HoNOSCA and the multi-informant ASEBA (CBCL, TRF, and YSR). We chose the ASEBA because it is widely used to assess the mental health of children and adolescents, and because many of the ASEBA scales and syndromes address similar aspects of mental health to those addressed by the HoNOSCA scales. We expected higher correlations between scales that assessed similar phenomena than between scales that assessed less similar phenomena. Second, we used regression analyses to investigate how well the ratings by each ASEBA informant (CBCL, TRF, and YSR) predicted the clinician-rated HoNOSCA scores, and how well these ASEBA informants' scores together predicted the HoNOSCA scores. Specifically, we investigated which informants' scores provided the best prediction for the different HoNOSCA scales and whether the different informants' scores made any unique contribution to the prediction of the HoNOSCA scores.