Table 10. PROMIS anxiety short form item set: Differential item function (DIF) results. Language subgroup comparison, English vs. Spanish for Hispanics only (n = 703; n = 335).

Item description	IRTPRO	lordif	Magnitude (NCDIF)	Effect Size T1
I felt fearful	U*	U	0.0260	-0.1357†
I felt anxious		U*	0.0493	0.1980†
I felt worried	NU; U		0.0026	-0.0433
I found it hard to focus on anything other than my anxiety		U	0.0063	0.0497
I felt nervous	U		0.0110	-0.0844
I felt uneasy			0.0050	-0.0577
I felt tense			0.0062	0.0244
My worries overwhelmed me		U	0.0089	0.0621
I felt like I needed help for my anxiety			0.0059	0.0595
Many situations made me worry	U	NU*; U*	0.1440	-0.3508†
I had difficulty calming down	U	U	0.0285	-0.1328†

Item 10 has the non-compensatory differential item functioning (NCDIF) value larger than the threshold (0.0960).

^†Indicates value above threshold of 0.10; bolded values are above 0.15.

^*Asterisks indicate significance after adjustment for multiple comparisons.

NU= Non-uniform DIF involving the discrimination parameters; U=Uniform DIF involving the location parameters.

For the lordif analyses, the Uniform and non-uniform DIF was determined using the likelihood ratio chi-square test. Uniform DIF is obtained by comparing the log likelihood values from models one and two. Non-uniform DIF is obtained by comparing the log likelihood values from models two and three. DIF was not detected using the pseudo R2 measures or the change in Beta criterion.