Patient self-report section of the ASES questionnaire: a Spanish validation study using classical test theory and the Rasch model

Table 3 Difficulty levels, standard errors, fit statistics and Rank order for two Rasch ASES-p models (n = 161)

Item no.	Item description	All ASES-p items^a					Function items^b
Item no.	Item description	δ (logit)	SE	Infit MNSQ	Outfit MNSQ	Rank order	δ (logit)	SE	Infit MNSQ	Outfit MNSQ	Rank order
Function
Item 7	Lift 10 lbs above shoulder	1.78	0.13	1.09	0.86	1	1.82	0.14	1.09	0.89	1
Item 8	Throw a ball overhand	1.07	0.13	0.82	0.72	2	1.09	0.13	0.81	0.73	2
Item 3	Wash back/do up bra	0.89	0.12	0.90	0.83	3	0.90	0.13	0.90	0.85	3
Item 2	Sleep on painful side	0.37	0.12	0.98	1.01	4	0.35	0.12	1.02	1.10	4
Item 6	Reach high shelf	0.36	0.12	0.85	0.79	5	0.35	0.12	0.86	0.82	4
Item 10	Do usual sport	−0.12	0.14	1.81	1.78	6	−0.16	0.14	1.86	1.90	5
Item 9	Do usual work	−0.28	0.12	0.73	0.74	7	−0.32	0.13	0.80	0.88	6
Pain
Item	How bad is your pain today	−0.33	0.12	1.26	1.74	8	-	-	-	-	-
Function
Item 1	Put on a coat	−0.97	0.13	0.71	0.75	9	−1.05	0.13	0.78	0.89	7
Item 5	Comb hair	−1.28	0.13	0.79	0.78	10	−1.38	0.13	0.81	0.83	8
Item 4	Manage toileting	−1.50	0.13	1.19	1.11	11	−1.61	0.14	1.23	1.16	9
Reliability index: Person/item		0.90/0.98					0.88/0.98
Separation index: Person/item		2.93/7.53					2.77/8.02
Variance %: Observed/Expected		59.7/59.5					60.4/60.2

δ (logit) level of item difficulty, based on the Rasch model, SE standard error, MNSQ mean square fit index, Rank order difficulty level, based on the δ (logit) measure. Variance refers to the Rasch model raw variance explained by the measures
^aIn this model, the original pain item was categorized as having 4 response options: 0–1 = No pain; 2–5 = some pain; 6–8 = a lot of pain; 9–10 = maximum pain. ^bItems 2 and 6 obtained the same δ (logit) estimation and where thus assigned the same rank order

ISSN: 1477-7525