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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for the Earth Science Scale, by Block and Item, Grade 8 Science National Main Assessment (Accommodations Not Permitted [R2]): 2000

NAEP Technical DocumentationIRT parameters for the earth science scale, by block and item, grade 8 science national main assessment (accommodations not permitted [R2]): 2000

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3	dj4
S5	1	K040801	0.59	-0.13	0.00	†	†	†	†
		K040802	0.51	-1.64	0.00	-0.94	0.94	†	†
		K040808	0.58	0.02	0.00	-1.46	1.46	†	†
		K040809	0.63	0.65	0.00	-1.34	1.34	†	†
	2	K040803	0.70	0.26	0.00	†	†	†	†
	3	K040804	0.89	1.64	0.00	-0.35	0.35	†	†
	4	K040805	0.76	1.47	0.00	-0.93	0.93	†	†
	5	K040806	0.98	1.61	0.00	†	†	†	†
S7	1	K102301	0.37	-1.00	0.00	-1.87	1.87	†	†
	2	K102101	0.90	-0.06	0.19	†	†	†	†
	3	K102201	0.99	-0.35	0.41	†	†	†	†
	4	K102001	0.43	0.22	0.00	-0.35	0.35	†	†
	5	K101701	1.72	1.55	0.27	†	†	†	†
	6	K101801	0.71	0.99	0.00	†	†	†	†
	7	K101901	0.84	0.11	0.31	†	†	†	†
	8	K097601	1.05	0.51	0.16	†	†	†	†
	9	K097801	0.54	2.23	0.23	†	†	†	†
	10	K097701	0.50	-0.64	0.25	†	†	†	†
	11	K098501	0.62	1.36	0.00	†	†	†	†
	12	K101301	0.84	0.76	0.26	†	†	†	†
	13	K101401	1.63	1.81	0.26	†	†	†	†
	14	K101501	0.59	2.62	0.19	†	†	†	†
	15	K101601	1.42	1.97	0.18	†	†	†	†
	16	K101201	0.63	1.96	0.00	-0.70	0.70	†	†
	17	K101101	0.77	-0.05	0.17	†	†	†	†
	18	K100901	0.70	-0.31	0.25	†	†	†	†
	19	K101001	0.67	1.81	0.23	†	†	†	†
	20	K097901	0.27	2.54	0.00	0.34	-0.34	†	†
S10	3	K094101	0.98	0.92	0.40	†	†	†	†
	4	K093501	0.53	-0.25	0.22	†	†	†	†
	6	K092601	0.79	-0.94	0.00	†	†	†	†
	7	K099701	0.33	1.89	0.33	†	†	†	†
	12	K102501	0.85	0.28	0.22	†	†	†	†
	13	K102401	1.36	0.77	0.13	†	†	†	†
S11	1	K042701	0.81	0.45	0.29	†	†	†	†
	2	K042702	0.99	0.53	0.21	†	†	†	†
	3	K042703	1.21	0.54	0.32	†	†	†	†
	7	K043101	0.58	0.08	0.00	-0.26	0.26	†	†
	8	K043102	0.43	-0.52	0.00	-0.74	0.74	†	†
	9	K043103	0.69	1.69	0.00	†	†	†	†
	11	K043301	0.86	0.78	0.23	†	†	†	†
S12	3	K047001	0.41	1.10	0.23	†	†	†	†
	6	K047301	0.85	1.91	0.00	†	†	†	†
	9	K047601	1.25	1.84	0.12	†	†	†	†
S13	2	K048301	0.93	-0.18	0.28	†	†	†	†
	6	K048701	0.42	0.59	0.27	†	†	†	†
	7	K048801	0.61	1.77	0.23	†	†	†	†
	13	K049401	0.58	1.93	0.00	1.42	-1.42	†	†
	14	K049402	0.44	0.31	0.00	0.61	-0.61	†	†
	15	K0494CL	0.23	2.33	0.00	-3.77	3.56	1.38	-1.18
S14	7	K036101	0.57	-1.63	0.00	†	†	†	†
	10	K0364CL	0.52	2.57	0.00	1.69	0.70	-2.40	†
	11	K036402	0.33	1.99	0.00	0.46	-0.46	†	†
S15	5	K037401	1.03	2.57	0.00	†	†	†	†
	7	K037601	0.61	0.62	0.00	0.50	-0.50	†	†
	10	K037801	0.78	1.01	0.20	†	†	†	†
	15	K038201	0.38	3.95	0.00	1.85	-1.85	†	†
S20	3	K093901	0.46	0.26	0.00	0.78	-0.78	†	†
	5	K090401	1.01	0.06	0.30	†	†	†	†
	8	K091101	0.85	-0.00	0.23	†	†	†	†
	9	K093801	0.46	2.86	0.33	†	†	†	†
	10	K091401	0.84	2.34	0.24	†	†	†	†
S21	6	K045701	0.46	0.12	0.00	0.58	-0.58	†	†
	10	K046101	0.70	0.14	0.13	†	†	†	†
† Not applicable; the number of item parameters estimated depends upon the IRT model used for scaling. NOTE: For item j, aj represents the discriminatory power of the item, bj represents a location parameter related to item difficulty, cj represents the guessing parameter, and dji is the category threshold parameter for category i. The c-parameter value is exactly zero for items scaled with the two-parameter logistic model or the generalized partial credit model. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000 Science Assessment.

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