This study offers an approach to testing for differential item functioning (DIF) in a recently developed measurement framework, referred to as D-scoring method (DSM). Under the proposed approach, called P–Z method of testing for DIF, the item response functions of two groups (reference and focal) are compared by transforming their probabilities of correct item response, estimated under the DSM, into Z-scale normal deviates. Using the liner relationship between such Z-deviates, the testing for DIF is reduced to testing two basic statistical hypotheses about equal variances and equal means of the Z-deviates for the reference and focal groups. The results from a simulation study support the efficiency (low Type error and high power) of the proposed P–Z method. Furthermore, it is shown that the P–Z method is directly applicable in testing for differential test functioning. Recommendations for practical use and future research, including possible applications of the P–Z method in IRT context, are also provided.

本研究提供了一种在最近开发的测量框架中测试差异项目功能 (DIF) 的方法，称为D评分方法 (DSM)。在所提出的方法（称为DIF 测试的P-Z方法）下，通过将在 DSM 下估计的正确项目响应的概率转换为 Z 尺度正态偏差来比较两组（参考和焦点）的项目响应函数。使用此类 Z 偏差之间的线性关系，对 DIF 的检验简化为检验关于参考组和焦点组的 Z 偏差的相等方差和相等均值的两个基本统计假设。模拟研究的结果支持所提出的P-Z的效率（低类型误差和高功率）方法。此外，还表明P-Z方法可直接应用于差分测试功能的测试。还提供了实际使用和未来研究的建议，包括P-Z方法在 IRT 环境中的可能应用。