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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → Item Response Theory Parameters → Mathematics Assessment Item Response Theory Parameters → IRT Parameters for Items in the Measurement Scale, by Block and Item, Grade 8 Mathematics Combined National and State Main Assessment: 2005

NAEP Technical DocumentationIRT parameters for items in the measurement scale, by block and item, grade 8 mathematics combined national and state main assessment: 2005

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3	dj4
M3	1	M075201	0.61	-0.73	0.18	†	†	†	†
	2	M075401	0.50	0.26	†	1.08	-1.08	†	†
	3	M075601	0.58	-0.01	†	-0.93	0.93	†	†
	18	M076001	0.47	1.34	†	-2.02	0.84	0.18	0.99
M4	6	M047201	0.89	-1.08	0.07	†	†	†	†
	14	M068008	0.40	2.09	†	0.25	-0.25	†	†
	17	M093601	0.84	1.54	†	1.48	-1.48	†	†
M5	3	M085601	1.21	-0.12	0.28	†	†	†	†
	4	M085501	1.25	0.58	0.19	†	†	†	†
	12	M047101	1.10	0.18	0.17	†	†	†	†
	17	M047901	1.20	1.31	0.00	†	†	†	†
M6	1	M140401	1.11	-0.61	0.12	†	†	†	†
	5	M140801	1.33	0.63	0.20	†	†	†	†
	7	M141001	1.25	0.09	0.17	†	†	†	†
M7	10	M144501	1.34	1.79	0.30	†	†	†	†
	12	M144701	1.01	0.94	0.30	†	†	†	†
M8	2	M013331	1.09	-1.21	0.26	†	†	†	†
	6	M073301	0.91	1.12	0.26	†	†	†	†
	12	M019201	1.44	1.42	0.15	†	†	†	†
M9	5	M072801	0.75	0.35	0.44	†	†	†	†
M10	2	M142101	0.87	-0.23	0.24	†	†	†	†
	6	M142501	1.25	1.53	0.11	†	†	†	†
	12	M143101	0.67	0.30	0.10	†	†	†	†
M11	7	M106301	1.13	0.07	0.00	†	†	†	†
	12	M106801	0.59	-1.06	0.13	†	†	†	†
	17	M107401	1.54	1.91	0.14	†	†	†	†
M12	2	M110001	1.08	0.92	0.19	†	†	†	†
	5	M110301	0.93	-0.62	0.09	†	†	†	†
† Not applicable; c parameters are not estimated for generalized partial credit models, and d parameters are not estimated for two-parameter or three-parameter logistic models. NOTE: For item j, aj represents the discriminatory power of the item, bj represents a location parameter related to item difficulty, cj represents the guessing parameter, and dji is the category threshold parameter for category i. The c parameter value is exactly zero for items scaled with the two-parameter logistic model. For item j, dji 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), 2005 Mathematics Assessment.

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