Impact of the Type and percentage of Differential Items Functioning on the ability parameter of individuals According to Parametric and Non-parametric Models of IRT

Abstract

This study aimed to investigate the impact of the type and percentage of Differential Items Functioning (10%, 20%, and 30%) on estimating individuals’ abilities according to the three-parameter model and Moken’s non-parametric model of item response theory. Experimental method was used to answer the questions of the study, by applying hypothetical tests, each of which has a length of (60) double-response items, generated using the (WinGen) software, to a sample of (2000) hypothetical individuals for each experimental condition. The study results showed differences in the ability parameter of the three-parameter logistic model and Moken's non-parametric model are not statistically significant for all experimental conditions related to the type and percentage of Differential Items Functioning and there are no differences in the ability parameter due to the type of model according to the experimental conditions related to the type and percentage of differential performance. The study recommended the use of Moken's non-parametric model when seeking the highest degree of reliability in the test.

Keywords: Differential Items Functioning, abilities of individuals, Three-parameter Logistic model, Moken model.