Table 5.

Item Parameter Estimates for 7 Mobility Items with Differential Item Functioning by Language

Item	Discrimination	1st Threshold	2nd Threshold	3rd Threshold	4th Threshold
F1_MOB2: I could ride a bike.	1.67	−2.27	−2.03	−1.68	−1.16
	2.32	−3.76	−2.93	−1.88	−0.96
F1_MOB3: I could do sports and exercise that other kids my age could do.	3.11	−1.92	−1.75	−1.14	−0.45
	2.54	−3.73	−2.85	−1.68	−0.76
F2_MOB 1: I could run a mile	1.13	−2.64	−1.78	−0.52	0.88
	1.63	−3.80	−2.87	−1.66	−0.25
F2 MOB4: I could walk upstairs without holding on to anything.	1.97	−2.79	−2.40	−1.96	−1.28
	2.96	−3.92	−2.81	−1.98	−0.96
F3 MOB5: I used a walker, cane or crutches to get around.	1.67	−3.56	−3.38	−2.88	−2.48
	2.66	−4.02	−2.73	−1.84	−1.00
F3 MOB10: I could turn my head all the way to the side.	1.16	−4.45	−3.97	−3.32	−2.28
	2.70	−3.94	−2.92	−1.97	−1.10
F4 MOB4: I could keep up when I played with other kids.	1.96	−2.90	−2.41	−1.63	−0.49
	2.52	−3.84	−2.81	−1.80	−0.72

Note: English parameters from DeWitt et al. (2011) are shown followed by parameters for Spanish sample after transformation to English-language metric. 1^st Threshold = Theta needed for 50% chance of responding with a lot of trouble, with some trouble, with a little trouble, or with no trouble; 2^nd Threshold = Theta needed for 50% chance of responding with some trouble, with a little trouble, or with no trouble; 3^rd Threshold = Theta needed for 50% chance of responding with a little trouble, or with no trouble; 4^th Threshold = Theta needed for 50% chance of responding with no trouble.

F3_MOB5 uses a different response scale: almost always, often, sometimes, almost never, and never.