Rasch analysis of the Brain Injury Screening Tool (BIST) in mild traumatic brain injury

BMC Neurology

Table 2 The BIST item fit statistics and frequency distribution of responses categories ordered by Item Difficulty

Item Number	Item description	Item Difficulty^a (Logits)	Item fit residual	χ2	p	Frequency distribution of response categories (0–3)
Item Number	Item description	Item Difficulty^a (Logits)	Item fit residual	χ2	p	Cat-0	Cat-1	Cat-2	Cat-3
14	I feel tired during the day	−0.86	− 0.94	2.21	0.33	18	34	34	18
1	Headache (my head hurts)	−0.76	0.71	1.07	0.59	11	53	29	11
15	I sleep a lot more or can’t fall asleep	− 0.54	1.51	0.99	0.61	27	27	34	16
11	I have trouble concentrating	− 0.37	−0.44	1.83	0.40	24	39	3	11
8	It takes me longer to think	−0.35	−1.31	1.39	0.50	25	40	27	12
9	I forget things	−0.31	−0.10	0.20	0.90	24	37	33	10
4	I don’t like loud noises	−0.34	0.70	0.25	0.88	25	36	30	11
12	I get easily annoyed	−0.21	−0.01	0.26	0.88	26	38	31	9
2	My neck hurts	−0.07	1.23	2.24	0.33	34	42	17	11
3	I don’t like bright lights	0.06	−0.52	0.42	0.81	33	36	27	8
13	I feel restless	0.53	0.39	0.41	0.81	46	38	14	6
10	I get confused easily	0.54	−0.76	1.46	0.48	48	30	20	6
7	I have trouble with my eyesight (vision)	0.68	1.57	3.63	0.16	47	35	18	4
5	If I close my eyes, I feel like I am at sea	0.98	−0.55	4.77	0.09	56	30	14	4
6	I feel like I will be sick	1.00	−0.04	0.54	0.77	61	30	9	4

χ2 Chi-square, p probability.
χ2 degree of freedom for items df = 2; Frequency distribution - extreme excluded; Response options in bold were endorsed by less than 10 people.
a = Item Difficulty (location) in logits ordered from easiest (Item 14, Tired) to most difficult (Item 6, Sick) items; negative logit values = easier items,
positive logit values = more difficult items.

ISSN: 1471-2377