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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 Geometry Subscale, Grade 8 Mathematics Combined National and State Assessment, by Item and Block: 2015

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

IRT parameters for items in the geometry 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	4	M350801	0.50	-0.87	†	0.05	-0.05	†	†
M3	10	M349501	0.26	-0.89	†	-4.78	4.78	†	†
M4	1	M151301	0.89	-0.73	0.08	†	†	†	†
M4	3	M151501	0.80	-0.38	†	0.27	-0.27	†	†
M5	3	M221203	0.58	0.90	†	2.29	-2.29	†	†
M5	7	M221501	0.66	-1.58	0.15	†	†	†	†
M6	8	M353401	0.56	0.09	†	-2.77	2.77	†	†
	10	M352401	0.77	0.25	0.12	†	†	†	†
	12	M355801	0.85	0.87	0.16	†	†	†	†
M7	2	M238801	0.83	-0.35	0.20	†	†	†	†
	6	M356101	0.59	1.36	0.15	†	†	†	†
	9	M356401	0.47	1.76	†	†	†	†	†
M8	2	M237101	1.80	1.07	0.24	†	†	†	†
	11	M236701	1.96	1.07	0.14	†	†	†	†
	15	M3173CL	1.02	1.22	†	0.57	-0.57	†	†
M9	2	M235901	1.20	0.50	0.12	†	†	†	†
M9	9	M238301	0.79	0.38	0.08	†	†	†	†
M10	4	M222701	0.56	-0.10	†	-3.29	3.29	†	†
M10	14	M223701	2.39	1.33	0.17	†	†	†	†
M11	2	M170901	1.02	-0.33	0.21	†	†	†	†
	10	M169101	0.92	2.13	0.34	†	†	†	†
	16	M171201	1.05	1.13	0.15	†	†	†	†
M12	3	M339501	1.16	-0.33	0.20	†	†	†	†
	4	M232001	0.64	0.20	0.10	†	†	†	†
	15	M234201	0.54	1.14	†	-0.91	0.91	†	†
† 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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