Psychometric Properties of the Bern Illegitimate Tasks Scale: Classical Test and Item Response Theories
Description
Combining a classical test theory and an item response theory (IRT), this study aimed to investigate psychometric properties of the Bern Illegitimate Task Scale (BITS) by measuring two conceptually separate dimensions capturing unnecessary tasks (poor understanding of their meaning) and unreasonable tasks (tasks unfairly assigned to an employee). Data collected among Polish employees in two samples (N = 965 and N = 803) were analysed. Results from classical test theory (parallel, exploratory and confirmatory factor analyses) indicated two correlated factors with four items each, confirming the theory of illegitimate tasks. This study is the first to report item functioning using IRT analysis (a graded response model) of each of the two dimensions of the scale. All items on each factor were very highly informative, including the difficulty and discrimination parameters and the test information function. All levels of unnecessary and unreasonable tasks were reliably captured by BITS items. Convergent and discriminant validities of both dimensions of the BITS were confirmed in relation to work overload, work performance and occupational well-being. We conclude that the BITS in the case of the Polish version is psychometrically suitable to use with the working populations.