Table 1.

Item Parameters of the 3PLM for R and F Groups.

DIF type	Area	$a_{\mathrm{R}}$	$b_{\mathrm{R}}$	$c_{\mathrm{R}}$	$a_{\mathrm{F}}$	$b_{\mathrm{F}}$	$c_{\mathrm{F}}$
Uniform	0.40	1.25	−0.25	0.20	1.25	0.25	0.20
Uniform	0.60	1.25	−0.38	0.20	1.25	0.38	0.20
Non-uniform	0.40	1.65	0.00	0.20	0.80	0.00	0.20
Non-uniform	0.60	0.79	0.00	0.20	0.45	0.00	0.20

Note. 3PLM = three-parameter logistic model; R = reference; F = focal; DIF = differential item functioning; a = discrimination parameter; b = difficulty parameter; c = guessing parameter.