As use of the public-domain International Personality Item Pool (IPIP) scales has grown significantly over the past decade (Goldberg, Johnson, Eber, Hogan, Ashton, Cloninger, & Gough, 2006) research on the psychometric properties of the items and scales have become increasingly important. This research study examines the IPIP scale constructed to measure the Five Factor Model (FFM) domain of Neuroticism (as measured by the NEO-PI-R) for occurrences of differential functioning at both the item and test level by gender and three age ranges using the DFIT framework (Raju, van der Linden, & Fleer, 1993) This study found six items that displayed differential item functioning by gender and three items that displayed differential item functioning by age. No differential functioning at the test level was found. Items demonstrating DIF and implications for potential scale revision are discussed. / Ph. D.

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. / Master of Science