Table 1

Summary of CAT simulations by underlying measurement model, DIF size, mean CAT measures and percentage of DIF items
IRT Model CAT to Full-Scale θ Correlation Mean Standard Error
1PL 2PL 1PL 2PL
DIF Size 0.42 0.63 0.42 0.63 0.42 0.63 0.42 0.63
    Diff. Mean 
    θ
    = 0
DIF % = 10 0.97 0.97 0.97 0.97 0.26 0.26 0.23 0.24
DIF % = 30 0.97 0.96 0.97 0.97 0.26 0.26 0.24 0.24
    Diff. Mean 
    θ
    = 1
DIF % = 10 0.97 0.97 0.97 0.97 0.26 0.26 0.24 0.24
DIF % = 30 0.97 0.96 0.97 0.97 0.26 0.26 0.24 0.24
Average 0.97 0.97 0.97 0.97 0.26 0.26 0.24 0.24

1PL = one-parameter item response model; 2PL = two-parameter item response model; CAT = computerized adaptive testing; DIF = differential item functioning; IRT = item response theory; θ = person measure.

Riley and Carle

Riley and Carle BMC Medical Research Methodology 2012 12:124   doi:10.1186/1471-2288-12-124

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