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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Mathematics Assessment IRT Parameters → IRT Parameters for Items in the Number Properties and Operations Subscale, Grade 8 Mathematics Combined National and State Assessment, by Item and Block: 2015

NAEP Technical DocumentationIRT Parameters for Items in the Number Properties and Operations Subscale, Grade 8 Mathematics Combined National and State Assessment, by Item and Block: 2015

IRT parameters for items in the number properties and operations subscale, grade 8 mathematics combined national and state assessment, by item and block: 2015
Block	Item	NAEP ID	a_j	b_j	c_j	d_j1	d_j2	d_j3	d_j4
M3	3	M350501	1.14	1.04	0.32	†	†	†	†
M3	11	M348601	1.05	0.86	0.10	†	†	†	†
M4	8	M152001	1.15	0.81	0.06	†	†	†	†
M5	6	M221401	0.98	1.18	0.21	†	†	†	†
	15	M222301	0.67	0.57	†	1.29	-1.29	†	†
	9	M221701	0.36	-0.05	†	†	†	†	†
M6	1	M351601	0.86	-0.17	0.12	†	†	†	†
	3	M353201	0.70	0.27	0.14	†	†	†	†
	11	M352001	0.87	0.51	0.06	†	†	†	†
	13	M232101	0.76	1.22	†	†	†	†	†
M7	3	M356201	0.77	0.29	0.14	†	†	†	†
	4	M235701	0.84	-1.38	†	†	†	†	†
	10	M357201	1.04	-0.75	0.12	†	†	†	†
	12	M3566CL	0.83	0.24	†	0.14	-0.14	†	†
M8	4	M234501	1.48	-0.52	0.12	†	†	†	†
	7	M236001	1.50	0.08	0.16	†	†	†	†
	13	M237801	1.00	-0.15	0.17	†	†	†	†
M9	1	M238701	1.23	-0.21	0.20	†	†	†	†
	6	M236601	1.29	-0.43	0.29	†	†	†	†
	10	M238101	1.08	0.20	0.33	†	†	†	†
	12	M234702	0.97	-0.02	†	0.05	-0.05	†	†
M10	1	M222401	0.66	-1.56	0.07	†	†	†	†
	7	M223001	0.98	-0.11	0.08	†	†	†	†
	12	M223501	0.69	-0.44	0.31	†	†	†	†
M11	1	M163101	0.75	-0.45	†	0.65	-0.65	†	†
	3	M122701	0.51	-0.15	0.15	†	†	†	†
	4	M119601	0.49	-0.39	0.06	†	†	†	†
	7	M169201	1.26	-0.21	0.22	†	†	†	†
M12	1	M232901	0.90	-2.17	0.15	†	†	†	†
	5	M233501	0.81	-0.05	†	†	†	†	†
	9	M231901	1.69	0.45	0.21	†	†	†	†
† 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_ji represents the category threshold parameter for category i. The c parameter value 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 Mathematics Assessment.

Last updated 17 November 2021 (ML)

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