The Narcissistic Grandiosity Scale; Psychometric Evaluation of the Iranian Version Publisher



Hoseingholizade S¹ ; Mousavi N² ; Effatpanah M³ ; Piryaei M⁴ Show Affiliations
Source: Journal of Forensic Psychology Research and Practice Published:2025

Abstract

This study evaluates the psychometric properties of the Persian version of the Narcissistic Grandiosity Scale (NGS). NGS measures within-person dynamics of grandiose narcissism at both trait- and state-level, making it possible to evaluate the grandiosity’s oscillations over time. This study assesses the psychometric properties of the Persian version of NGS. The sample comprises 426 participants, predominantly females (59.06%), with 40.03% married, 39.7% aged between 18–28, mostly residing in Tehran (65%). Reliability assessments were Cronbach’s Alpha, test-retest coefficient, and confirmatory factor analysis (CFA). For the convergent and discriminant validity, the Rosenberg Self-Esteem Scale (RSES), Brief Pathological Narcissism Inventory -Grandiosity (B-PNI-G), and Vulnerability (B-PNI-V)- were administered aside from NGS. The pilot study (45 participants) showed high consistency and fluent translation. For the total score, Cronbach’s alpha was 0.915, and alphas were found in the range of 0.905–0.918 for items. The test-retest reliability coefficient was 0.904. The 6-item version of NGS showed excellent reliability (Cronbach’s alpha = 0.915) and consistency (test-retest reliability = 0.904). CFA indicated its suitability (CFI = 0.970, TLI = 0.950, RMSEA = 0.076, SRMR = 0.037). Correlations with RSES, B-PNI-G, and B-PNI-V were significant. The findings confirm the 6-item version of NGS as an effective tool for assessing narcissistic grandiosity in non-clinical Iranian samples, offering valuable insights into cultural variations in narcissistic traits and states within the Iranian context. © 2024 Taylor & Francis Group, LLC.