The Narcissistic Personality Inventory: Test-retest stability and internal consistency

The Narcissistic Personality Inventory (NPI) is a self-report measure that assesses subclinical levels of narcissism. It evolved through a 54-item, four-factor version to its current 40-item, seven-factor version. This study focuses on the 40-item NPI that produces a full-scale narcissism score and seven-factor-based subscale scores: authority, exhibitionism, superiority, entitlement, exploitativeness, self-sufficiency, and vanity. This study is the first to examine its test-retest reliability. The stability coefficients are expected to be high as personality characteristics are presumed to represent enduring and stable traits. The internal consistency is also investigated, particularly as this version has fewer items, yet a greater number of factor-based subscales than its predecessor. The alpha coefficients produced by data from test, retest, and previously published research are compared. The NPI was administered to 175 American college students, and re-administered 13 weeks later. The NPI demonstrated significant test-retest correlations for all scales. Across all results, only the full-scale and authority subscale possessed adequate (α > .70) internal consistency, thus raising questions regarding the utility of the remaining scales.