Only complementary voices tell the truth: a reevaluation of validity in multi-informant approaches of child and adolescent clinical assessments

Multi-informant approaches are thought to be key to clinical assessment. Classical theories of psychological measurements assume that only convergence among different informants' reports allows for an estimate of the true nature and causes of clinical presentations. However, the integration of multiple accounts is fraught with problems because findings in child and adolescent psychiatry do not conform to the fundamental expectation of convergence. Indeed, reports provided by different sources (self, parents, teachers, peers) share little variance. Moreover, in some cases informant divergence may be meaningful and not error variance. In this review, we give an overview of conceptual and theoretical foundations of valid multi-informant assessment and discuss why our common concepts of validity need revaluation.