Table 2.

IRT model item parameters for adolescent and parent CIDI inattention and hyperactivity-impulsivity items¹

		Youth reports Slope threshold		Parent reports Slope threshold
I.	Inattention
	Poor attention to detail	1.02	−0.13	3.33	0.88
	Difficulty sustaining attention	0.80	0.33	2.37	1.14
	Seem not to listen	1.10	−0.36	2.46	0.98
	Not follow through on instructions	0.88	0.45	2.45	0.81
	Difficulty organizing tasks	0.85	0.84	2.18	1.24
	Avoids tasks with sustained effort	0.98	0.21	2.64	0.96
	Loses things necessary for tasks	0.88	0.25	1.83	1.19
	Easily distracted	1.08	−0.09	2.55	0.81
	Forgetful in daily activities	1.14	0.06	3.11	1.03
	(n)	(1136)2		(8290)2
II.	Hyperactivity-impulsivity
	Fidgets or squirms	0.91	−0.40	2.82	1.14
	Leaves seat	0.91	0.33	2.83	1.22
	Runs about or climbs	0.91	−0.22	3.39	0.98
	Difficulty playing quietly	0.91	−0.10	2.53	1.34
	On the go or driven by a motor	0.91	−0.10	2.13	1.12
	Talks excessively	0.91	−0.05	1.34	1.16
	Blurts out answers	0.91	0.36	1.73	1.41
	Difficulty waiting turn	0.91	0.68	2.43	1.32
	Interrupts or intrudes on others	0.91	0.24	1.72	1.10
	(n)	(1512)2		(8290)2

¹The two-parameter model fits better than the one-parameter model (which assumes constant slopes across items) for all scales other than the youth-report hyperactivity-impulsivity scale. Results are consequently reported for the one-parameter model for the latter scale and for the two-parameter model for the other scales.

²Sample sizes differ because the symptom questions were administered to all parents who knew the child before the age of seven (n = 8290) but not to all adolescents. Adolescents were administered an initial screening question separately for AD and HD that determined whether or not they would subsequently be administered the full set of symptom question. A total of 1136 adolescents endorsed the AD screening question, while 1512 endorsed the HD screening question.