Evaluating the Longitudinal Item and Category Stability of the SF-36 Full and Summary Scales Using Rasch Analysis

Table 18

Differential Item Functioning (DIF) for SF-36 mental health scale Rasch analysis for six waves of data collection based on marital status and area of residence.

	Wave 1				Wave 2				Wave 3
	Marital status		Urban and Regional		Marital status		Urban and Regional		Marital status		Urban and Regional
SF36 ITEM  No.	SUMMARY DIF CHI-SQUARE (DIF = 2)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability	SUMMARY DIF  CHI-SQUARE (DIF = 2)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability	SUMMARY DIF  CHI-SQUARE (DIF = 2)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability
17:Q5A	3.13	.206	0.00	.720	0.05	.975	-0.17	.122	0.07	.969	0.00	.978
18:Q5B	6.16		0.00	.799	0.41	.814	0.00	.347	0.59	.745	0.00	.165
19:Q5C	4.23	.119	0.00	.505	0.17	.922	-0.30	.066	0.79	.673	0.00	.484
20:Q6	62.55		-0.09	.058	6.62		0.00	.056	0.00	1.000	0.00	.415
23:Q9A	8.45		0.00	.101	0.00	1.000	-0.05	.498	0.05	.979	0.00	.725
24:Q9B	14.83		0.09		0.41	.813	0.00	.553	11.22		0.02	.093
25:Q9C	62.48		0.12		29.94		0.48	.087	0.01	.996	0.07
26:Q9D	9.01		-0.07		0.16	.925	-0.07	.476	22.89		-0.06
27:Q9E	8.72		0.00	.741	0.49	.782	0.37		0.57	.750	0.00	.207
28:Q9F	17.18		0.08		20.01		0.00	.401	0.73	.694	0.05	.004
29:Q9G	5.04	.079	0.00	.719	3.76	.150	0.52		11.42		0.00	.815
30:Q9H	13.46		-0.06		8.62		0.00	.176	3.70	.155	-0.07
31:Q9I	1.75	.414	0.00	.224	0.51	.773	-0.18	.308	0.00	1.000	0.00	.299
32:Q10	14.70		0.00	.207	0.11	.947	0.00	.165	2.75	.250	0.00	.978
	Wave 4				Wave 5				Wave 6
SF36 ITEM; No.	Marital status		Urban and Regional		Marital status		Urban and Regional		Marital status		Urban and Regional
	SUMMARY DIF; CHI-SQUARE (DIF = 1)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability	SUMMARY DIF; CHI-SQUARE (DIF = 2)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability	SUMMARY DIF; CHI-SQUARE (DIF = 2)	PROB.	DIF CONTRAST	Mantel- Haenszel Probability
17:Q5A	0.00	1.000	0.00	.618	0.07	.966	-0.03	.986	0.94	.623	-0.18
18:Q5B	0.00	1.000	0.00	.639	2.43	.294	0.00	.395	0.39	.824	0.00	.543
19:Q5C	0.00	1.000	0.00	.497	0.71	.701	0.20	.271	0.59	.744	-0.19
20:Q6	0.00	1.000	0.00	.779	6.37		-0.02	.337	2.26	.320	-0.03	.162
23:Q9A	0.00	1.000	0.00	.900	1.95	.373	0.19	.254	1.18	.551	-0.04	.176
24:Q9B	6.95		0.00	.384	13.76		0.00	.784	3.06	.213	0.00	.580
25:Q9C	0.00	1.000	0.06		6.84		-0.68	.078	0.77	.678	0.08	.371
26:Q9D	0.00	1.000	0.00	.544	13.70		-0.02	.118	2.06	.354	0.00	.923
27:Q9E	0.00	1.000	0.00	.537	3.30	.189	-0.08	.720	1.67	.430	0.06	.215
28:Q9F	0.00	1.000	0.00	.687	0.87	.644	0.00	.819	0.43	.806	0.00	.408
29:Q9G	0.00	1.000	0.00	.694	0.20	.908	0.27	.570	0.63	.729	0.03	.278
30:Q9H	6.10		0.00	.297	4.86	.086	0.05	.065	0.08	.962	0.00	.419
31:Q9I	0.00	1.000	-0.05	.112	1.10	.574	0.48	.170	0.04	.981	-0.04	.664
32:Q10	0.00	1.000	0.00	.414	1.56	.456	0.08		0.05	.979	0.00	.434

Notes. PROB. = probability; ; ; .