Development and validation of an ultra-brief scale to measure moral intelligence: The Moral Intelligence Scale

OBJECTIVE To develop and validate a scale for measuring moral intelligence, i.e. the Moral Intelligence Scale (MIS). METHOD Construct validity of the MIS was evaluated through corrected item–total correlations and confirmatory factor analysis. Concurrent validity was assessed using the Patient Health Questionnaire-4 (PHQ-4) and the Multidimensional Scale of Perceived Social Support (MSPSS). Reliability was examined through Cronbach’s alpha and the intraclass correlation coefficient. Additionally, Receiver Operating Characteristic (ROC) analysis was conducted to identify the optimal cut-off point for the MIS, with the PHQ-4 serving as the external criterion. RESULTS Corrected item–total correlations and confirmatory factor analysis supported the unidimensional structure of the MIS, confirming that the final version comprises four items loading on a single factor. Evidence for concurrent validity was strong, as statistically significant correlations were observed between MIS scores and both the PHQ-4 and the MSPSS, consistent with theoretical expectations. Reliability analyses indicated satisfactory internal consistency, with a Cronbach’s alpha of 0.724, and excellent test–retest reliability, as reflected by an intraclass correlation coefficient of 0.989 (95% confidence interval = 0.984–0.992, p-value < 0.001). Furthermore, ROC analysis identified 17 as the optimal cut-off point, classifying individuals with MIS scores ≥ 17 as having high levels of moral intelligence. CONCLUSIONS The MIS is a 1-factor 4-item scale with great reliability and validity. By offering a concise yet robust measure of moral intelligence, the MIS provides scholars and practitioners with a practical tool for exploring the role of moral reasoning and ethical behavior in diverse domains, thereby contributing to the advancement of research and interventions aimed at fostering moral development and integrity.