Table 3

Average WOMAC functional item calibrations, SE, and INFIT statistic ordered by misfitting

WOMAC function: difficulty with	Number	Average item calibration (logits)	SE	INFIT statistic (MSQ)
Osteoarthritis
Getting in and out of bath	655	−0.19	0.02	1.53
Going down stairs	655	−0.27	0.02	1.41
Heavy chores	655	−0.69	0.03	1.25
Going upstairs	655	−0.47	0.02	1.20
Lying down	655	0.50	0.03	1.13
Bending	655	−0.24	0.02	1.07
Putting on socks	655	0.05	0.02	0.99
Shopping	655	−0.16	0.02	0.98
Walking on flat ground	655	0.22	0.03	0.94
Getting on and off the toilet	655	0.30	0.03	0.93
Sitting	655	0.51	0.03	0.92
Standing	655	0.04	0.02	0.89
Taking off socks	655	0.21	0.03	0.88
Arising from bed	655	−0.19	0.02	0.85
Arising from sitting	655	0.11	0.02	0.81
Light chores	655	0.33	0.03	0.78
Getting in and out of a car	655	−0.07	0.02	0.73
Rheumatoid arthritis
Getting in and out of bath	1013	−0.30	0.02	1.54
Going down stairs	1013	−0.20	0.02	1.31
Lying down	1013	0.46	0.02	1.26
Bending	1013	−0.20	0.02	1.20
Heavy chores	1013	−0.81	0.02	1.20
Walking on flat ground	1013	0.17	0.02	1.17
Going up stairs	1013	−0.25	0.02	1.16
Putting on socks	1013	−0.01	0.02	1.08
Taking off socks	1013	0.11	0.02	0.94
Standing	1013	0.11	0.02	0.91
Arising from sitting	1013	0.06	0.02	0.88
Sitting	1013	0.48	0.02	0.85
Getting on and off toilet	1013	0.29	0.02	0.84
Shopping	1013	−0.10	0.02	0.83
Light chores	1013	0.22	0.02	0.83
Arising from bed	1013	−0.06	0.02	0.75
Getting in and out of a car	1013	0.02	0.02	0.63
Fibromyalgia
Going downstairs	537	0.02	0.03	1.37
Getting in and out of bath	537	−0.15	0.03	1.29
Heavy chores	537	−1.04	0.03	1.28
Going upstairs	537	−0.43	0.03	1.24
Lying down	537	0.28	0.03	1.24
Light chores	537	0.25	0.03	1.01
Standing	537	0.08	0.03	0.99
Putting on socks	537	0.20	0.03	0.98
Bending	537	−0.29	0.03	0.98
Shopping	537	−0.16	0.03	0.96
Taking off socks	537	0.31	0.03	0.95
Sitting	537	0.31	0.03	0.94
Arising from sitting	537	−0.05	0.03	0.92
Getting on and off toilet	537	0.45	0.03	0.90
Walking on flat ground	537	0.29	0.03	0.87
Getting in and out of a car	537	0.02	0.03	0.73
Arise from bed	537	−0.09	0.03	0.70

Negative calibrations indicate more difficult items. The more positive the score the easier the item. INFIT statistics >1.2–1.3 indicate that the item does not contribute to the underlying construct. INFIT (MNSQ) values of <0.7–0.8 indicate items that are muted.