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

Table 13

SF-36 mental health scale Rasch analysis item statistics for six waves of data collection.

	Wave 1			Wave 2			Wave 3
SF36 ITEM	MEASURE	MODEL S.E.	PTMEA CORR.	MEASURE	MODEL S.E.	PTMEA CORR.	MEASURE	MODEL S.E.	PTMEA CORR
17:Q5A	1.35	0.01	0.31	1.38	0.01	0.30	1.49	0.02	0.27
18:Q5B	1.57	0.01	0.31	1.62	0.02	0.29	1.75	0.02	0.27
19:Q5C	1.38	0.01	0.30	1.41	0.01	0.28	1.50	0.02	0.26
20:Q6	1.51	0.01	-0.09	1.78	0.02	-0.02	1.41	0.01	-0.02
23:Q9A	-0.03	0.01	0.17	-0.06	0.01	0.22	-0.12	0.01	0.27
24:Q9B	-1.28	0.01	0.46	-1.47	0.01	0.43	-1.54	0.01	0.41
25:Q9C	-1.84	0.01	0.45	-2.04	0.01	0.40	-2.08	0.02	0.40
26:Q9D	0.21	0.01	0.20	0.30	0.01	0.18	0.30	0.01	0.26
27:Q9E	-0.16	0.01	0.22	-0.24	0.01	0.26	-0.29	0.01	0.30
28:Q9F	-1.25	0.01	0.46	-1.33	0.01	0.39	-1.32	0.01	0.40
29:Q9G	-0.90	0.01	0.44	-0.93	0.01	0.39	-0.88	0.01	0.39
30:Q9H	0.63	0.01	0.27	0.72	0.01	0.25	0.74	0.01	0.28
31:Q9I	-0.55	0.01	0.37	-0.50	0.01	0.31	-0.42	0.01	0.31
32:Q10	-0.65	0.01	0.28	-0.65	0.01	0.22	-0.55	0.01	0.19
	Wave 4			Wave 5			Wave 6
SF36 ITEM	MEASURE	MODEL S.E.	PTMEA CORR	MEASURE	MODEL S.E.	PTMEA CORR	MEASURE	MODEL S.E.	PTMEA CORR.
17:Q5A	1.47	0.02	0.28	1.48	0.02	0.30	1.51	0.02	0.29
18:Q5B	1.76	0.02	0.28	1.77	0.02	0.30	1.81	0.03	0.32
19:Q5C	1.51	0.02	0.27	1.51	0.02	0.28	1.53	0.02	0.28
20:Q6	1.19	0.01	0.04	1.01	0.02	0.03	0.96	0.02	0.05
23:Q9A	-0.14	0.01	0.23	-0.21	0.01	0.24	-0.29	0.01	0.26
24:Q9B	-1.52	0.01	0.40	-1.49	0.02	0.40	-1.47	0.02	0.37
25:Q9C	-2.07	0.02	0.35	-1.92	0.02	0.39	-1.91	0.02	0.35
26:Q9D	0.30	0.01	0.23	0.31	0.01	0.19	0.29	0.01	0.22
27:Q9E	-0.34	0.01	0.27	-0.41	0.01	0.27	-0.53	0.01	0.29
28:Q9F	-1.30	0.01	0.40	-1.25	0.01	0.42	-1.22	0.02	0.41
29:Q9G	-0.80	0.01	0.39	-0.75	0.01	0.44	-0.72	0.01	0.43
30:Q9H	0.75	0.01	0.29	0.69	0.01	0.23	0.69	0.02	0.27
31:Q9I	-0.34	0.01	0.33	-0.30	0.01	0.35	-0.27	0.01	0.32
32:Q10	-0.48	0.01	0.17	-0.44	0.01	0.17	-0.39	0.01	0.17

Note: MODEL S.E. = Model Standard Error; PTMEA CORR = Point Measure Correlation.