© 2019 Elsevier B.V. Background: The Affective Reactivity Index (ARI) is a brief instrument originally designed as a self- and parent report. However, the view of teachers, who can observe social situations that may give rise to irritability, is relevant. The goal is to provide the measurement qualities of the ARI score as reported by teachers. Method: Children formed part of a longitudinal study on behavior problems in Barcelona (Spain) and they were assessed when they were 7 (N = 471) and 11 years old (N = 454) with questionnaires about psychopathology, anger and aggressive behavior, and a diagnostic interview answered by the parents, youths and teachers. Confirmatory factor analysis, measurement invariance, reliability and validity were studied for the ARI answered by teachers. Results: The 6-item, 1-factor model fitted well. Almost full metric invariance and partial scalar invariance was obtained across sex and over age. The ARI scores largely converged with other teacher-reported measures of anger and irritability, and with other measures of psychopathology, aggressive behavior, and callous-unemotional traits at a medium level. The associations with parent's measures were medium to low, and very low for child self-reported measures. The ARI scores significantly differentiated children with and without psychopathology and functional impairment, both cross-sectionally and longitudinally. Limitations: Only one child self-report measure of irritability included. Limited internal consistency of some scale scores. Findings are mostly generalizable to Spanish children. Conclusions: ARI could be a suitable instrument for measuring irritability as reported by teachers. The teacher's view can be useful when planning treatment by helping to identify treatment targets.
- MEASUREMENT INVARIANCE
- OPPOSITIONAL DEFIANT DISORDER
- PSYCHOMETRIC PROPERTIES