Table 2.

ASQoL Items with Significant Differential Item Functioning Between Subgroups of Autistic Adults

ASQoL Item #	Grouping Variable	χ2	df	p FDR	UIDS	ESSD	Parameters
6	Sex	24.22	6	0.001	0.451	0.606†	d2, d3, d4 (all F>M)
7	Sex	44.40	6	<0.001	0.614	0.935†	d1, d2, d3, d4 (all F>M)
8	Sex	29.48	6	0.002	0.432	0.480	d2, d3 (all F>M)
3	Gender	13.17	5	0.022	0.107	0.206	d1 (F>M)
6	Gender	19.84	6	0.006	0.411	0.549†	d3, d4 (all F>M)
7	Gender	35.95	6	<0.001	0.560	0.856†	d1, d2, d3, d4 (all F>M)
8	Gender	17.54	6	0.010	0.398	0.463	d2, d3 (all F>M)
1/4 (testlet)	Anxiety	29.02	9	0.001	0.335	0.057	d2 (Anx>NoAnx)
7	Anxiety	18.16	6	<0.001	0.489	−0.847†	d3, d4 (all NoAnx>Anx)
3	Neuroticism	14.95	5	0.011	0.266	−0.574†	d1, d2 (all LowN>HighN)
7	Neuroticism	26.84	6	<0.001	0.394	−0.551†	a2, d1, d2, d3 (all LowN>HighN)
7	Alexithymia	56.53	6	<0.001	0.720	1.299†	a1, d1, d2, d3, d4 (all HighA>LowA)
8	Alexithymia	16.25	6	0.012	0.350	0.439	a1 (HighA>LowA)

Note. Results indicate omnibus Wald tests of differential item functioning (DIF) using the iterative anchor-selection method of Cao et al. (2017). P-values are corrected using the Benjamini-Hochberg false discovery rate procedure (p_FDR). Parameters that were significantly different between groups when tested alone with follow-up Wald tests (p_FDR < 0.05) are indicated in the Parameters column. UIDS = unsigned item difference in the sample (absolute expected item score difference between individuals of the same latent trait level); ESSD = expected score standardized difference (in Cohen’s d metric); a₁/a₂ = slope parameter; d₁-d₄ = item intercept parameters (i.e., item “difficulty” parameters). Larger values of a parameters indicate that the item is more strongly related to the latent trait in one group, whereas larger values of d parameters indicate that a given item response is endorsed at lower latent trait levels in one group relative to the other. F = female; M = male; Anx = co-occurring anxiety disorder; NoAnx = no co-occurring anxiety disorder; LowN = below median neuroticism score; HighN = above median neuroticism score; HighA = alexithymia T-score ≥60; LowA = alexithymia T-score < 60.

^†Practically significant DIF (i.e., |ESSD| > 0.5)