Table 1.

Differential Item Functioning for Boston Naming Test items

				Reference Group			Focal Group
Item	Hypothesis	G 2	d.f.	a	b	g	a	B	g
01 - bed	Unconstrained	11.5*	3	−0.38	3.38	0.49	0.27	−31.37	0.50
	1	0.0	1	−0.38	3.36	0.49	0.33	−23.65	0.49
	2	0.0	1	−0.38	3.37	0.49	−0.38	22.77	0.49
	3	11.5*	1	0.34	−6.71	0.50	0.34	−6.71	0.50
02 - tree	Unconstrained	9.2*	3	−37.11	1.33	0.47	−1.16	8.18	0.50
	1	0.1	1	−37.02	1.33	0.46	−1.89	8.08	0.46
	2	0.0	1	−30.92	1.35	0.46	−30.92	4.59	0.46
	3	9.2*	1	−7.02	2.89	0.50	−7.02	2.89	0.50
03 - pencil	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
04 - house	Unconstrained	1.6	3	0.23	−38.28	0.50	0.55	−4.01	0.50
05 - whistle	Unconstrained	1.3	3	2.21	−1.25	0.53	1.08	−2.16	0.49
06 - scissors	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
07 - comb	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
08 - flower	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
09 - saw	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
10 - toothbrush	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
11 - helicopter	Unconstrained	0.9	3	1.05	−2.32	0.50	1.39	−1.56	0.48
12 - broom	Unconstrained	0.0	3	0.18	−99.04	0.50	0.18	−99.04	0.50
13 - octopus	Unconstrained	0.0	3	2.52	−0.26	0.30	2.10	−0.10	0.36
14 - mushroom	Unconstrained	2.6	3	2.77	−1.10	0.54	2.27	−0.71	0.49
15 - hanger	Unconstrained	0.7	3	−0.03	72.33	0.50	0.74	−3.51	0.50
16 - wheelchair	Unconstrained	1.0	3	52.58	−1.88	0.53	60.84	−1.58	0.48
17 - camel	Unconstrained	6.9*	3	1.24	−2.56	0.50	3.35	−0.93	0.48
	1	0.1	1	1.21	−2.59	0.50	3.43	−0.90	0.50
	2	0.4	1	3.05	−1.92	0.51	3.05	−0.93	0.51
	3	6.4*	1	1.57	−1.68	0.50	1.57	−1.68	0.50
18 - mask	Unconstrained	2.8	3	0.55	−3.04	0.50	1.55	−1.14	0.48
19 - pretzel	Unconstrained	2.2	3	1.56	0.28	0.32	1.57	−0.13	0.40
20 - bench	Unconstrained	1.0	3	1.00	−2.83	0.50	0.89	−8.04	0.50
21 - racquet	Unconstrained	5.4*	3	72.22	−0.59	0.29	61.86	−0.63	0.55
	1	5.4*	1	61.86	−0.62	0.34	61.86	−0.62	0.34
	2	0.0	1	61.86	−0.62	0.34	61.86	−0.62	0.34
	3	0.0	1	61.86	−0.62	0.34	61.86	−0.62	0.34
22 - snail	Unconstrained	23.2*	3	47.94	−0.79	0.44	2.52	0.03	0.39
	1	0.2	1	47.81	−0.80	0.42	2.58	0.06	0.42
	2	1.8	1	2.86	−0.95	0.39	2.86	0.07	0.39
	3	21.2*	1	1.75	−0.25	0.44	1.75	−0.25	0.44
23 - volcano	Unconstrained	7.2*	3	16.48	−0.56	0.37	2.57	−0.17	0.41
	1	0.0	1	8.25	−0.64	0.32	2.40	−0.25	0.33
	2	2.0	1	2.66	−0.68	0.30	2.66	−0.23	0.30
	3	7.1*	1	2.19	−0.42	0.33	2.19	−0.42	0.33
24 - seahorse	Unconstrained	1.2	3	2.77	−0.28	0.28	1.92	0.11	0.32
25 - dart	Unconstrained	17.4*	3	13.04	0.18	0.24	1.98	−0.36	0.40
	1	0.0	1	9.16	0.15	0.20	1.82	−0.54	0.20
	2	4.0*	1	2.24	0.16	0.19	2.24	−0.42	0.19
	3	17.0*	1	2.77	−0.10	0.26	2.77	−0.10	0.26
26 - canoe	Unconstrained	2.8	3	0.94	−0.96	0.49	1.73	−0.39	0.45
27 - globe	Unconstrained	25.1*	3	15.08	−1.03	0.45	2.23	0.14	0.44
	1	0.0	1	29.91	−1.03	0.40	2.16	0.10	0.40
	2	1.4	1	2.40	−1.12	0.42	2.40	0.15	0.42
	3	24.2*	1	1.44	−0.16	0.51	1.44	−0.16	0.51
28 - wreath	Unconstrained	6.7*	3	0.37	−1.67	0.50	2.60	−0.24	0.48
	1	0.2	1	0.37	−1.61	0.51	2.66	−0.21	0.51
	2	6.5*	1	2.30	−0.16	0.62	2.30	−0.16	0.62
	3	0.0	1	2.30	−0.16	0.62	2.30	−0.16	0.62
29 - beaver	Unconstrained	9.6*	3	2.47	0.82	0.18	1.25	0.56	0.35
	1	0.0	1	2.74	0.71	0.16	1.12	0.29	0.16
	2	0.7	1	1.17	1.29	0.15	1.17	0.30	0.15
	3	13.0*	1	1.45	0.51	0.20	1.45	0.51	0.20
30 - harmonica	Unconstrained	26.1*	3	597.85	0.25	0.42	48.64	−0.00	0.73
	1	21.5*	1	49.46	0.06	0.49	47.13	−0.01	0.49
	2	0.0	1	47.82	0.08	0.49	47.82	−0.01	0.49
	3	4.6*	1	48.19	0.03	0.58	48.19	0.03	0.58
31 - rhinoceros	Unconstrained	0.0	3	2.93	−0.00	0.32	2.27	0.20	0.38
32 - acorn	Unconstrained	8.5*	3	21.90	0.01	0.25	2.25	0.38	0.42
	1	0.0	1	14.17	−0.00	0.20	1.72	0.12	0.20
	2	8.9*	1	1.99	0.16	0.25	1.99	0.19	0.25
	3	1.0	1	2.02	0.21	0.27	2.02	0.21	0.27
33 - igloo	Unconstrained	6.5*	3	41.34	0.48	0.19	6.08	0.17	0.31
	1	0.0	1	20.42	0.46	0.15	4.69	0.08	0.15
	2	0.5	1	5.21	0.43	0.15	5.21	0.10	0.15
	3	11.7*	1	6.61	0.21	0.20	6.61	0.21	0.20
34 - stilts	Unconstrained	15.5*	3	1.33	−0.10	0.43	4.19	0.41	0.30
	1	4.8*	1	1.29	−0.15	0.40	4.57	0.47	0.40
	2	10.8*	1	3.76	0.42	0.43	3.76	0.44	0.43
	3	0.0	1	3.65	0.42	0.41	3.65	0.42	0.41
35 - dominoes	Unconstrained	1.6	3	0.36	−3.14	0.50	0.80	−2.33	0.50
36 - cactus	Unconstrained	1.3	3	26.13	−0.29	0.44	2.44	−0.45	0.45
37 - escalator	Unconstrained	12.3*	3	6.96	−0.45	0.38	1.92	0.19	0.49
	1	0.6	1	6.53	−0.47	0.34	1.64	−0.02	0.34
	2	4.3*	1	1.81	−0.52	0.38	1.81	0.06	0.38
	3	7.4*	1	1.48	−0.13	0.40	1.48	−0.13	0.40
38 - harp	Unconstrained	11.9*	3	57.93	−0.01	0.70	61.79	0.01	0.43
	1	11.2*	1	59.24	0.02	0.64	59.60	0.02	0.64
	2	0.0	1	59.59	0.02	0.64	59.59	0.02	0.64
	3	0.7	1	59.19	0.02	0.61	59.19	0.02	0.61
39 - hammock	Unconstrained	45.5*	3	4.22	−0.58	0.49	2.41	0.56	0.27
	1	12.9*	1	4.25	−0.58	0.49	3.14	0.76	0.49
	2	30.6*	1	2.62	0.51	0.55	2.62	0.76	0.55
	3	2.0	1	2.16	0.62	0.46	2.16	0.62	0.46
40 - knocker	Unconstrained	4.8*	3	4.22	0.48	0.35	1.73	0.15	0.42
	1	0.0	1	3.79	0.46	0.33	1.59	0.02	0.33
	2	1.0	1	1.74	0.53	0.31	1.74	0.05	0.31
	3	5.0*	1	2.06	0.22	0.35	2.06	0.22	0.35
41 - pelican	Unconstrained	0.1	3	3.66	0.19	0.21	1.57	0.56	0.28
42 - stethoscope	Unconstrained	12.8*	3	2.36	1.07	0.17	2.81	0.39	0.33
	1	0.0	1	2.41	0.93	0.12	2.39	0.24	0.12
	2	0.1	1	2.40	0.94	0.12	2.40	0.24	0.12
	3	17.7*	1	2.94	0.40	0.18	2.94	0.40	0.18
43 - pyramid	Unconstrained	17.3*	3	22.81	−0.27	0.27	2.42	0.31	0.28
	1	0.0	1	23.77	−0.27	0.21	2.32	0.26	0.21
	2	4.8*	1	2.60	−0.34	0.21	2.60	0.28	0.21
	3	17.0*	1	1.91	0.11	0.23	1.91	0.11	0.23
44 - muzzle	Unconstrained	15.0*	3	1.26	−0.07	0.42	2.84	0.69	0.32
	1	2.3	1	1.22	−0.13	0.39	3.06	0.75	0.39
	2	12.5*	1	3.00	0.70	0.46	3.00	0.78	0.46
	3	0.2	1	2.81	0.74	0.43	2.81	0.74	0.43
45 - unicorn	Unconstrained	8.3*	3	19.63	0.07	0.27	1.80	0.63	0.39
	1	0.0	1	18.33	0.05	0.23	1.44	0.40	0.23
	2	9.5*	1	1.57	0.28	0.24	1.57	0.42	0.24
	3	1.9	1	1.56	0.43	0.26	1.56	0.43	0.26
46 - funnel	Unconstrained	3.1	3	0.43	−1.60	0.51	1.96	−0.11	0.49
47 - accordion	Unconstrained	31.1*	3	−175.57	1.52	0.53	2.83	1.22	0.65
	1	31.1*	1	38.40	1.47	0.76	38.40	1.47	0.76
	2	0.0	1	38.40	1.47	0.76	38.40	1.47	0.76
	3	0.0	1	38.40	1.47	0.76	38.40	1.47	0.76
48 - noose	Unconstrained	41.6*	3	0.79	−1.68	0.50	2.45	0.43	0.31
	1	40.3*	1	2.42	0.56	0.63	2.68	0.66	0.63
	2	0.3	1	2.66	0.55	0.63	2.66	0.66	0.63
	3	1.0	1	2.34	0.56	0.56	2.34	0.56	0.56
49 asparagus	Unconstrained	15.2*	3	1.02	0.74	0.39	1.27	−0.48	0.50
	1	0.0	1	1.09	0.53	0.37	1.18	−0.72	0.37
	2	0.2	1	1.18	0.54	0.38	1.18	−0.71	0.38
	3	15.3*	1	1.69	−0.11	0.42	1.69	−0.11	0.42
50 - compass	Unconstrained	23.8*	3	0.50	0.60	0.50	2.26	1.38	0.28
	1	23.9*	1	2.81	1.48	0.41	3.11	1.51	0.41
	2	0.0	1	3.07	1.48	0.40	3.07	1.50	0.40
	3	0.0	1	3.02	1.50	0.40	3.02	1.50	0.40
51 - latch	Unconstrained	0.3	3	0.41	0.16	0.50	0.71	0.28	0.50
52 - tripod	Unconstrained	0.0	3	67.80	2.22	0.21	1.66	0.87	0.20
53 - scroll	Unconstrained	3.5	3	89.84	0.73	0.28	2.55	0.48	0.27
54 - tongs	Unconstrained	33.7*	3	0.45	−1.38	0.50	3.06	0.99	0.32
	1	33.2*	1	2.75	0.94	0.56	2.99	0.98	0.56
	2	0.2	1	2.99	0.94	0.55	2.87	0.96	0.55
	3	0.2	1	2.87	0.96	0.54	1.94	−0.02	0.54
55 - sphinx	Unconstrained	0.0	3	13.38	2.16	0.15	2.15	1.48	0.13
56 - yoke	Unconstrained	0.0	3	12.18	2.20	0.32	1.93	0.91	0.27
57 - trellis	Unconstrained	0.8	3	12.95	0.76	0.39	1.74	0.71	0.28
58 - palette	Unconstrained	0.0	3	307.48	0.99	0.18	1.67	1.19	0.19
59 - protractor	Unconstrained	0.0	3	18.13	0.83	0.22	1.26	1.41	0.23
60 - abacus	Unconstrained	0.6	3	−1951.24	−4.50	0.25	−21.37	−4.54	0.26

Note. “Unconstrained” = No parameters constrained.

“1” = asymptote (g) parameter constrained equal for reference and focal groups.

“2” = both asymptote and slope parameters constrained to be equal.

“3” = asymptote, slope, and threshold parameters constrained to be equal.

^*χ² significant, p < .05.