Differential Item Functioning of the Mindfulness Scale Items by Gender Using the Rating Scale Model within Item Response Theory Framework among Students at Taiz and Aden Universities

Abstract

This study aimed to detect differential item functioning (DIF) of the Mindfulness Scale items by gender using the Rating Scale Model (RSM) within the framework of Item Response Theory (IRT), and to examine the model-data fit. The study adopted a descriptive psychometric design. The scale was administered to a main sample of 709 male and female students from Taiz and Aden Universities, following verification of the instrument’s preliminary psychometric properties on a pilot sample.

To achieve the study objectives, the assumptions of the Rating Scale Model were verified, and item-model fit was examined using Chi-Square fit statistic. Item difficulty parameters and step difficulty parameters were estimated, and marginal reliability and the test information function were computed. Differential item functioning was detected using the likelihood ratio test.

Results confirmed that the assumptions of the Rating Scale Model were met and that the scale data adequately fit the model. Thirty out of thirty-four items demonstrated acceptable fit indices, whereas four items failed to meet acceptable fit criteria according to the Chi-Square statistic. Furthermore, results revealed DIF in only two items, while the remaining items showed no significant DIF by gender. These findings support the validity of the Mindfulness Scale for use with students at Taiz and Aden Universities and provide additional evidence of its sound psychometric properties and measurement fairness.