Table 3. Item Response Theory Parameters for Items With Suspected DIF by Race.

Module, construct, and item	a	b 1	b 2	DIF type	R 2	∆β	ESSD	ETSSDa	UETSDSa
Module 1.1, SA, gazeb
White	2.60	−1.61	−0.18	Uniform	0.012	0.02	0.08	0.05	0.91
Black/African American	2.24	−1.55	0.12
Module 1.2, SA, shared enjoymentc
White	2.01	−0.07	1.14	Uniform	0.01	0.03	0.26	0.008	0.41
Black/African American	1.79	0.07	1.56
Module 2.2, RRB, repetitive interestsd
White	0.54	0.69	1.86	Nonuniform	0.01	0.02	1.22	0.03	0.34
Black/African American	0.63	1.80	2.66
Module 3, SA, facial expressions
White	1.72	0.05	2.00	Nonuniform	0.01	0.002	0.11	0.04	0.25
Black/African American	1.32	−0.12	2.15
Module 3, SA, quality of overtures
White	2.58	−0.51	1.63	Uniform	0.01	0.03	−0.20	NA	NA
Black/African American	2.47	−0.38	1.95
Module 3, SA, showing
White	1.04	0.77	3.29	Uniform	0.01	0.01	0.22	NA	NA
Black/African American	1.11	0.49	2.86
Module 3, SA, initiation of joint attention
White	1.10	0.15	2.40	Uniform	0.002	0.005	0.22	NA	NA
Black/African American	1.08	−0.13	2.32
Module 3, RRB, stereotyped language
White	0.86	0.26	3.02	Nonuniform	0.001	0.02	0.22	NA	NA
Black/African American	0.57	0.76	4.55

Abbreviations: a, item discrimination; b, item difficulty for each level of response; DIF, differential item functioning; ESSD, expected standardized score difference; ETSSD, expected test standardized score difference; NA, not applicable; RRB, repetitive, restrictive behavior; SA, social affect; UETSDS, unsigned expected test score difference in the sample.

^a ETSSD and UETSDS are test-level statistics that assess the effect of differential functioning of all items on the total score.

^b Module 1.1 refers to module 1, no words.

^c Module 1.2 refers to module 1, words.

^d Module 2.1 refers to module 2, <5 years; module 2.2 refers to module 2, >5 years.