Assessment of Differential Item Functioning in Health-Related Outcomes: A Simulation and Empirical Analysis with Hierarchical Polytomous Data

Table 2

Power for between-group variable by type of analysis and manipulated factors.

Variable			Item discrimination
			Low (0.5–0.99)				High (1.5–2)
	Cluster		DIF = 0.4		DIF = 0.8		DIF = 0.4		DIF = 0.8
			OLR	HOLR	OLR	HOLR	OLR	HOLR	OLR	HOLR
0.05	50	5	0.312	0.287	0.82	0.802	0.773	0.753	1	1
		10	0.555	0.529	0.982	0.981	0.971	0.966	1	1
		20	0.859	0.836	1	1	1	1	1	1
	100	5	0.571	0.55	0.979	0.977	0.975	0.973	1	1
		10	0.829	0.817	1	1	0.999	0.999	1	1
		20	0.982	0.979	1	1	1	1	1	1
	200	5	0.83	0.816	1	1	0.998	0.998	1	1
		10	0.984	0.981	1	1	1	1	1	1
		20	1	1	1	1	1	1	1	1
0.25	50	5	0.305	0.284	0.812	0.787	0.763	0.746	1	1
		10	0.55	0.51	0.982	0.972	0.967	0.955	1	1
		20	0.835	0.807	1	1	1	1	1	1
	100	5	0.557	0.53	0.979	0.975	0.975	0.968	1	1
		10	0.83	0.81	1	1	0.999	0.999	1	1
		20	0.971	0.963	1	1	1	1	1	1
	200	5	0.831	0.821	1	1	0.999	0.998	1	1
		10	0.985	0.983	1	1	1	1	1	1
		20	1	1	1	1	1	1	1	1
0.45	50	5	0.303	0.28	0.817	0.786	0.778	0.755	1	1
		10	0.534	0.487	0.983	0.976	0.971	0.964	1	1
		20	0.819	0.767	1	1	1	1	1	1
	100	5	0.551	0.525	0.98	0.977	0.974	0.969	1	1
		10	0.831	0.796	1	1	0.999	0.998	1	1
		20	0.974	0.954	1	1	1	1	1	1
	200	5	0.814	0.796	1	1	1	1	1	1
		10	0.979	0.969	1	1	1	1	1	1
		20	1	1	1	1	1	1	1	1