Table 5.

Item parameters and values for the SS X² fit index and LR DIF statistics for the anxiety items

Item stem	Item parameters					SS X2 fit index			LR DIF
	a	b1	b2	b3	b4	X2	df	p	X2	df	p
I felt scared.	1.89	−0.25	0.59	1.72	2.52	32	37	0.683	8.4	5	0.136
I worried about what could happen to me.	1.84	−0.24	0.48	1.54	2.21	49	39	0.134	6.5	5	0.261
I worried when I went to bed at night.	1.83	0.25	0.91	1.83	2.57	27	37	0.884	12.7	5	0.026
I felt worried.	1.81	−0.78	0.25	1.59	2.65	48	36	0.090	2.5	5	0.776
I felt like something awful might happen.	1.71	−0.43	0.51	1.75	2.65	44	37	0.207	10.7	5	0.058
I was worried I might die.	1.71	0.86	1.54	2.44	2.90	26	30	0.699	1.8	5	0.876
I woke up at night scared.	1.65	0.89	1.43	2.28	2.94	28	32	0.672	10.6	5	0.060
I worried when I was at home.	1.64	0.40	1.22	2.61	3.30	34	34	0.478	3.5	5	0.623
I felt nervous.	1.51	−0.85	0.18	1.86	2.85	58	37	0.016	8.8	5	0.117
I thought about scary things.	1.50	−0.40	0.51	1.85	2.64	28	37	0.846	11.6	5	0.041
I got scared really easy.	1.49	0.29	1.16	2.07	2.74	43	35	0.274	9.6	5	0.087
I was afraid that I would make mistakes.	1.48	−0.68	0.29	1.91	2.86	36	38	0.558	2.2	5	0.821
It was hard for me to relax.	1.42	−0.33	0.63	1.83	2.71	52	41	0.120	5.1	5	0.404
I worried when I was away from home.	1.32	0.77	1.50	2.59	3.16	29	36	0.785	2.6	5	0.761
I was afraid of going to school.	1.09	1.21	2.01	3.02	3.96	19	29	0.912	4.7	5	0.454
Items set aside due to LD
I felt afraid.	1.61	0.26	1.18	2.31	3.31	33	35	0.559	7.6	5	0.180
It was hard for me to stop worrying.	1.87	0.06	0.85	1.76	2.52	24	35	0.930	3.5	5	0.623
Items set aside due to low discrimination
I felt relaxed.	0.71	−1.07	1.26	3.59	4.80	39	39	0.468	5.1	5	0.404

The scale for the item parameters is set such that the distribution of anxiety in the reference population (represented by the NC portion of the sample) is standardized, mean 0 variance 1, as is conventional for reporting IRT parameters