Exploring the Evidence to Interpret Differential Item Functioning via Response Process Data

Evaluating differential item functioning (DIF) in assessments plays an important role in achieving measurement fairness across different subgroups, such as gender and native language. However, relying solely on the item response scores among traditional DIF techniques poses challenges for researchers and practitioners in interpreting DIF. Recently, response process data, which carry valuable information about examinees' response behaviors, offer an opportunity to further interpret DIF items by examining differences in response processes. This study aims to investigate the potential of response process data features in improving the interpretability of DIF items, with a focus on gender DIF using data from the Programme for International Assessment of Adult Competencies (PIAAC) 2012 computer-based numeracy assessment. We applied random forest and logistic regression with ridge regularization to investigate the association between process data features and DIF items, evaluating the important features to interpret DIF. In addition, we evaluated model performance across varying percentages of DIF items to reflect practical scenarios with different percentages of DIF items. The results demonstrate that the combination of timing features and action-sequence features is informative to reveal the response process differences between groups, thereby enhancing DIF item interpretability. Overall, this study introduces a feasible procedure to leverage response process data to understand and interpret DIF items, shedding light on potential reasons for the low agreement between DIF statistics and expert reviews and revealing potential irrelevant factors to enhance measurement equity.