Analysis of the Reliability of the Leadership Practices Inventory in the Item Response Theory Framework

Abstract

The paper examines the psychometric properties of the leadership practices inventory (LPI) in the framework of item response theory (IRT). The LPI assesses five dimensions (i.e. leadership practices) of transformational leadership and consists of 30 items. IRT is a model-based theory that relates the characteristics of questionnaire items (item parameters) and characteristics of individuals (latent variables) to the probability of choosing each of the response categories. The theory does not assume that the instrument is equally reliable for all levels of the latent variable examined. Samejima's graded response model was used to estimate LPI item characteristics, such as item difficulty and item discrimination power. The results show that some items are redundant in the sense they contribute little to the overall precision of the instrument. Moreover, the LPI seems to be most precise and reliable for respondents with low to medium leadership competence, whereas it becomes increasingly unreliable for high-quality leaders. These findings suggest that the LPI is best used for training and development purposes, but not for leader selection purposes.