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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 Data Analysis, Statistics, and Probability Subscale, Grade 8 Mathematics Combined National and State Assessment, by Item and Block: 2015

NAEP Technical DocumentationIRT Parameters for Items in the Data Analysis, Statistics, and Probability Subscale, Grade 8 Mathematics Combined National and State Assessment, by Item and Block: 2015

IRT parameters for items in the data analysis, statistics, and probability 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	6	M351001	0.59	-0.69	0.14	†	†	†	†
	9	M349401	0.80	0.85	0.09	†	†	†	†
	14	M351301	1.73	0.85	0.18	†	†	†	†
M4	6	M151801	0.62	-1.07	0.12	†	†	†	†
M4	11	M152301	0.27	2.53	0.07	†	†	†	†
M5	11	M221901	0.69	0.81	0.16	†	†	†	†
M5	14	M222201	0.69	1.39	0.13	†	†	†	†
M6	9	M349701	0.98	0.80	0.20	†	†	†	†
M6	15	M352201	0.81	0.22	0.10	†	†	†	†
M7	5	M354801	1.51	0.46	0.07	†	†	†	†
M7	14	M357101	1.58	0.87	0.11	†	†	†	†
M8	5	M239001	1.00	-0.97	†	0.84	-0.84	†	†
M8	9	M236201	0.83	-0.66	0.25	†	†	†	†
M9	4	M235301	1.19	0.45	0.23	†	†	†	†
M9	11	M236801	1.11	0.08	0.21	†	†	†	†
M10	6	M222901	1.00	-0.28	0.06	†	†	†	†
	10	M223301	0.42	0.62	†	-0.39	0.39	†	†
	13	M223601	1.02	0.50	0.12	†	†	†	†
M11	8	M171101	1.31	0.23	0.11	†	†	†	†
	11	M162901	0.64	-0.29	†	0.91	-0.91	†	†
	15	M167901	0.59	1.35	†	-1.18	1.18	†	†
M12	8	M233801	0.95	1.02	0.26	†	†	†	†
M12	11	M231501	0.58	0.26	†	†	†	†	†
† 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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