Assessing the Differential Functioning of Items and Tests of a Polytomous Employee Attitude Survey

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Virginia Tech

Dimensions of a polytomous employee attitude survey were examined for the presence of differential item functioning (DIF) and differential test functioning (DTF) utilizing Raju, van der Linden, & Fleer's (1995) differential functioning of items and tests (DFIT) framework. Comparisons were made between managers and non-managers on the 'Management' dimension and between medical staff and nurse staff employees on both the 'Management' and 'Quality of Care and Service' dimensions. 2 out of 21 items from the manager/non-manager comparison were found to have significant DIF, supporting the generalizability of Lynch, Barnes-Farell, and Kulikowich (1998). No items from the medical staff/nurse staff comparisons were found to have DIF. The DTF results indicated that in two out of the three comparisons 1 item could be removed to create dimensions free from DTF. Based on the current findings implications and future research are discussed.

DFIT, DIF, Attitude Assessment, IRT, Differential Item Functioning