Measurement precision of the disability for back pain scale-by applying Rasch analysis

Table 3 Step difficulties represented with logit unit of the ODI with 6-level scaling

Item	δ _{i 1}	δ _{i 2}	δ _{i 3}	δ _{i 4}	δ _{i 5}	Disordering of the step difficulties (*)
						_1–2	_2–3	_3–4	_4–5
ODI 1: Pain intensity	−2.61	−1.34	0.99	0.86	1.62			*
ODI 2: Personal care	−0.19	−0.62	0.96	2.01	2.02	*
ODI 3: Lifting	−2.65	−0.16	−0.94	−1.01	2.30		*	*
ODI 4: Walking	−1.67	−0.40	0.02	0.95	2.38
ODI 5: Sitting	−1.08	−0.99	−0.01	1.36	2.40
ODI 6: Standing	−2.36	−0.99	−1.12	0.14	1.94		*
ODI 7: Sleeping	−1.35	0.82	0.91	1.33	1.35
ODI 8: Sex life	−1.26	0.44	−1.34	0.16	0.39		*
ODI 9: Social life	−1.48	−1.03	−0.47	0.67	1.46
ODI 10: Traveling	−2.01	−0.72	0.39	−0.48	0.42			*

δ, thresholds: the measure ability in the equally probable of two successive responses.
δ _{i 1}: indicates the threshold belonging to the first and the second responses.

ISSN: 1477-7525