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Using Weighted Sum Scores to Close the Gap Between DIF Practice and Theory
Author(s) -
Guo Hongwen,
Dorans Neil J.
Publication year - 2019
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/jedm.12258
Subject(s) - differential item functioning , matching (statistics) , statistics , item response theory , mathematics , latent variable , variable (mathematics) , simple (philosophy) , odds , econometrics , differential (mechanical device) , psychometrics , logistic regression , mathematical analysis , philosophy , epistemology , engineering , aerospace engineering
We make a distinction between the operational practice of using an observed score to assess differential item functioning (DIF) and the concept of departure from measurement invariance (DMI) that conditions on a latent variable. DMI and DIF indices of effect sizes, based on the Mantel‐Haenszel test of common odds ratio, converge under restricted conditions if a simple sum score is used as the matching or conditioning variable in a DIF analysis. Based on theoretical results, we demonstrate analytically that matching on a weighted sum score can significantly reduce the difference between DIF and DMI measures over what can be achieved with a simple sum score. We also examine the utility of binning methods that could facilitate potential operational use of DIF with weighted sum scores. A real data application was included to show this feasibility.