Fig 1.
Flowchart of the selection of articles reporting detection of Differential Item Functioning (DIF).
DIF: Differential Item Functioning, CFA: Confirmatory Factorial Analysis, IRT: Item Response Theory, PROMIS: Patient Reported Outcomes Measurement Information System, 2PL: Two Parameters Logistic model, LORDIF: Logistic Ordinal Regression Differential Item Functioning using IRT [20].
Table 1.
Practices related to the Differential Item Functioning (DIF) detection and results within the item response theory framework.
Table 2.
Factors manipulated in the simulation study and values studied in the four kinds of Differential Item Functioning (DIF).
Fig 2.
Item characteristic curves in the reference and focal groups and Differential Item Functioning (DIF) effect-size used in the simulation model for the four kinds of DIF.
δi: item location parameter for the item category i, Δ = {0.25, 0.5, 1}, the latent trait scale on the X-axis is given in logits.
Table 3.
Results of the multivariate analysis of variance of the measurement bias for the four kinds of Differential Item Functioning (DIF) studied.