Table 3.

Item Characteristics Based on a Rating Scale Model (FJS-CAT knee version)

# Item Content	MNSQ		Item Difficulty	Category Thresholds
	Infit	Outfit		1–2	2–3	3–4	4–5
01 ⁎in bed at night	1.48	2.67	1.03
02 ⁎sitting > 1 h	1.33	2.21	0.86
03 walking > 15 min	1.05	0.96	0.75	− 0.01	0.52	0.80	1.69
04 taking a bath/shower	1.32	1.53	2.00	1.24	1.77	2.05	2.94
05 travelling in a car	1.20	1.62	1.25	0.49	1.02	1.30	2.19
06 climbing stairs	1.24	1.22	− 0.60	− 1.36	− 0.83	− 0.55	0.34
07 walking on uneven ground	0.81	0.76	− 0.43	− 1.19	− 0.66	− 0.38	0.51
08 getting up from a low sitting position	1.24	1.17	− 1.53	− 2.29	− 1.76	− 1.48	− 0.59
09 standing for longer	0.99	0.88	− 0.27	− 1.03	− 0.5	− 0.22	0.67
10 housework or gardening	1.03	1.00	0.26	− 0.50	0.03	0.31	1.20
11 taking a walk/hiking	0.87	0.77	− 0.69	− 1.45	− 0.92	− 0.64	0.25
12 favorite sport	0.94	0.94	− 0.75	− 1.51	− 0.98	− 0.70	0.19

Final 10-item model: RMSEA 0.06.

^⁎Item discarded due to poor model data fit.