The value of item response theory in invariance testing

Abstract

The goal of the current study was to assess the Employee Engagement Instrument (EEI) from an item response theory (IRT) perspective, with a specific focus on measurement invariance for annual turnover. The sample comprised 4 099 respondents from all business sectors in South Africa. This article describes the logic and procedures used to test for factorial invariance across groups in the context of construct validation. The procedures included testing for configural and metric invariance in the framework of multiple-group confirmatory factor analysis (CFA). The results confirmed the factor analytic structure of the model fit for some of the individual scales of the EEI. The measurement invariance of the EEI as a function of annual turnover was confirmed. However, the results indicated that the EEI needs to be refined for future research.