Objectives: To assess the psychometric properties of the Persian version of the short Schema Mode Inventory (SMI).
Methods: The short SMI was translated into Persian by three clinical psychology professors and then back-translated into English by two professors in English language. Between 2017 and 2018, patients from Iran Psychiatric Hospital and Rasoul Akram Hospital who were diagnosed with personality disorder in Axis II by a psychiatrist and had minimum education of middle school were included. Controls included students and staff of the Iran Medical Sciences University who had minimum education of middle school. All participants were asked to complete the short SMI and the Young Schema Questionnaire - Short Form (YSQ-SF). Internal consistency (Cronbach's alpha), test-retest reliability, confirmatory factor analysis, internal correlation of schema mode subscales, and correlation between short SMI and YSQ-SF were assessed.
Results: Of 406 participants, 205 (50.7%) were patients and 201 (49.3%) were controls. The fitness indices indicated that the 14-factor model was reliable, with χ2 = 12917.97, p < 0.001, df = 5795, χ2/df = 2.23, CFI = 0.96, NNFI = 0.96 SRMR = 0.08, and RMSEA = 0.05. The internal consistency of the short SMI was satisfactory (M = 0.94). Among 34 participants in the control group who completed the short SMI again after 2 weeks, test-retest reliability was high (Pearson correlation coefficient = 0.88, p < 0.001). The short SMI and YSQ-SF correlated strongly in terms of the overall scale and most subscales. The patient and control groups differed significantly in most subscales.
Conclusions: Psychometric properties of the Persian version of the short SMI showed good validity and reliability. It can be used in clinical and research settings.
Keywords: Reproducibility of results; Schema therapy; Validation study.