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

IRT parameters for items in the measurement 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	2	M348701	0.93	-0.93	0.14	†	†	†	†
	7	M3511CL	0.90	-0.47	†	1.16	-1.16	†	†
	12	M3498CL	0.49	1.34	†	-0.25	-0.82	1.07	†
M4	2	M151401	0.98	1.00	0.10	†	†	†	†
	4	M151601	0.96	1.40	†	-0.38	0.38	†	†
	12	M152401	1.02	0.71	0.08	†	†	†	†
M5	1	M221201	1.08	0.15	0.36	†	†	†	†
	2	M221202	1.27	0.49	0.34	†	†	†	†
	4	M221204	0.65	0.88	†	1.48	-1.48	†	†
M6	2	M3519CL	0.69	-0.12	†	-0.62	0.62	†	†
M6	4	M353001	0.74	0.22	0.28	†	†	†	†
M7	1	M354501	0.78	0.59	0.25	†	†	†	†
M7	8	M355401	0.97	1.95	0.15	†	†	†	†
M8	1	M236101	0.45	0.42	0.04	†	†	†	†
	3	M234601	0.88	-0.39	0.11	†	†	†	†
	14	M236401	0.83	-1.17	0.20	†	†	†	†
M9	3	M235001	0.74	-1.67	0.13	†	†	†	†
	8	M237601	0.97	-0.68	0.20	†	†	†	†
	14	M238401	1.50	0.39	0.10	†	†	†	†
M10	2	M222501	0.82	-0.10	0.17	†	†	†	†
M10	9	M223201	0.86	1.67	0.28	†	†	†	†
M11	5	M121801	0.96	0.54	0.56	†	†	†	†
M11	13	M167301	1.38	0.86	0.17	†	†	†	†
M12	2	M231401	1.21	0.67	0.50	†	†	†	†
	6	M233101	0.99	-0.73	0.12	†	†	†	†
	13	M339601	0.51	-0.14	0.13	†	†	†	†
† 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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