Partial credit trees meet the partial gamma coefficient for quantifying DIF and DSF in polytomous items

Henninger M, Radek J, Sengewald MA, Strobl C (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Behaviormetrika Behaviormetric Society of Japan

Book Volume: 52

Pages Range: 221-257

Journal Issue: 2

DOI: 10.1007/s41237-024-00252-3

Abstract

Partial credit trees (PCtree) from the model-based recursive partitioning framework combine the partial credit measurement model for polytomous items with decision trees from machine learning. This method allows researchers to investigate measurement invariance by detecting differential item and differential step functioning (DIF/DSF) in a data driven way. In this manuscript, we extend PCtrees by an effect size measure for DIF/DSF in polytomous items, the partial gamma coefficient from psychometrics. We evaluate this extension of PCtrees in a series of simulation studies. Our results show that the partial gamma coefficient supports researchers in evaluating whether splits in the tree are meaningful, identifying DIF and DSF items, and can stop the tree from growing in case of negligible effect sizes. Furthermore, we assess and implement a correction for item-wise testing that is particularly crucial in longer tests. Finally, we illustrate the extension of PCtrees using data from the LISS panel to showcase its enhanced interpretability.

Involved external institutions

Universität Basel CH Switzerland (CH) Leibniz-Institut für Bildungsverläufe e.V. (LIfBi) DE Germany (DE) University of Zurich / Universität Zürich (UZH) CH Switzerland (CH)

How to cite

APA:

Henninger, M., Radek, J., Sengewald, M.A., & Strobl, C. (2025). Partial credit trees meet the partial gamma coefficient for quantifying DIF and DSF in polytomous items. Behaviormetrika, 52(2), 221-257. https://doi.org/10.1007/s41237-024-00252-3

MLA:

Henninger, Mirka, et al. "Partial credit trees meet the partial gamma coefficient for quantifying DIF and DSF in polytomous items." Behaviormetrika 52.2 (2025): 221-257.

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