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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for Items in the Earth and Space Sciences Subscale, Grade 12 Science National Assessment, by Item and Block: 2015

NAEP Technical DocumentationIRT Parameters for Items in the Earth and Space Sciences Subscale, Grade 12 Science National Assessment, by Item and Block: 2015

IRT parameters for items in the earth and space sciences subscale, grade 12 science national assessment, by item and block: 2015
Block	Item	NAEP ID	a_j	b_j	c_j	d_j₁	d_j₂	d_j₃	d_j₄
S3	4	K133301	0.40	2.16	†	-0.60	0.60	†	†
S3	5	K1572CL	0.31	1.19	†	1.64	2.59	-4.23	†
S4	2	K128001	0.25	-1.52	0.29	†	†	†	†
	10	K157701	1.53	1.91	0.26	†	†	†	†
	11	K157801	0.83	0.32	0.23	†	†	†	†
	12	K157901	0.63	0.88	†	0.59	-0.59	†	†
	18	K130201	1.03	1.03	0.30	†	†	†	†
S5	4	K143901	0.77	0.14	0.28	†	†	†	†
	5	K143902	1.95	2.05	0.17	†	†	†	†
	6	K143903	0.60	1.78	†	0.39	-0.39	†	†
	10	K130301	0.56	0.51	†	1.34	-1.34	†	†
S6	2	K135001	0.82	1.91	†	0.23	-0.04	-0.18	†
	3	K134701	0.87	1.25	0.30	†	†	†	†
	5	K130901	0.23	0.65	0.31	†	†	†	†
	11	K140501	0.66	0.73	0.26	†	†	†	†
	12	K143201	0.86	-0.48	0.22	†	†	†	†
	17	K130701	1.57	1.23	0.28	†	†	†	†
S7	3	K131401	0.64	0.46	0.31	†	†	†	†
	7	K131901	0.89	1.43	0.14	†	†	†	†
	13	K141901	1.30	0.54	0.22	†	†	†	†
	14	K158301	0.71	1.40	†	0.46	-0.46	†	†
	16	K132101	1.44	0.04	0.21	†	†	†	†
S8	2	K140801	1.31	0.74	0.20	†	†	†	†
	9	K142401	0.64	0.22	†	0.32	-0.32	†	†
	12	K137651	0.45	0.88	†	-1.03	-0.05	1.08	†
	13	K137652	1.32	1.43	0.35	†	†	†	†
	16	K137001	0.97	0.94	0.24	†	†	†	†
S9	2	K175501	1.44	0.49	0.16	†	†	†	†
	7	K175901	1.10	0.93	0.16	†	†	†	†
	11	K1776CL	0.34	0.20	†	-3.81	3.33	0.47	†
	18	K176301	1.73	0.72	0.22	†	†	†	†
S10	2	K177401	0.66	0.77	0.25	†	†	†	†
	6	K172901	0.36	-0.34	†	0.19	-2.73	2.54	†
	12	K173401	0.72	0.23	0.29	†	†	†	†
S11	2	K139301	0.94	-0.06	0.33	†	†	†	†
	9	K125802	0.92	1.66	†	0.55	-0.55	†	†
	10	K125803	0.67	1.46	†	-0.60	0.60	†	†
	15	K141801	1.42	1.72	0.29	†	†	†	†
S12	2	K133001	0.56	1.97	0.23	†	†	†	†
	5	K128701	0.35	1.18	†	0.51	0.57	-2.07	0.99
	15	K142101	0.68	0.49	0.27	†	†	†	†
S13	2	K129501	1.11	1.81	0.48	†	†	†	†
	4	K126001	0.61	1.40	†	0.34	0.15	0.07	-0.57
	13	K144601	0.88	0.84	0.25	†	†	†	†
† Not applicable; c parameters are not estimated for the two-parameter logistic model or generalized partial credit models, and d parameters are not estimated for two-parameter or three-parameter logistic models. NOTE: For item j, a_j represents the discriminatory power of the item, b_j represents a location parameter related to item difficulty, c_j represents the guessing parameter, and d_j_i represents the category threshold parameter for category i. The c parameter is assumed to be exactly zero and is not estimated for items scaled with the two-parameter logistic model. For item j, d_ji may not sum to zero because of rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

Last updated 17 November 2021 (ML)

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