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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for Items in the Earth and Space Sciences Subscale, Grade 8 Science Combined National and State Assessment, by Item and Block: 2015

NAEP Technical DocumentationIRT Parameters for Items in the Earth and Space Sciences Subscale, Grade 8 Science Combined National and State Assessment, by Item and Block: 2015

IRT parameters for items in the earth and space sciences subscale, grade 8 science 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
S3	1	K114201	0.45	-0.56	0.35	†	†	†	†
	2	K114101	1.09	1.29	0.32	†	†	†	†
	3	K113901	0.48	-0.26	†	1.03	-1.03	†	†
	8	K113102	0.62	0.78	0.32	†	†	†	†
	14	K113701	0.44	1.02	†	0.66	0.64	-0.23	-1.08
	16	K113301	0.79	0.73	0.35	†	†	†	†
S4	3	K122201	1.51	0.88	0.35	†	†	†	†
	9	K122901	0.75	-0.40	0.20	†	†	†	†
	12	K123001	0.70	0.21	0.21	†	†	†	†
	15	K122602	0.44	1.24	†	-0.08	0.08	†	†
	17	K122501	0.42	0.28	0.20	†	†	†	†
	18	K121801	1.06	1.61	0.23	†	†	†	†
S5	1	K120701	1.13	0.31	0.53	†	†	†	†
	4	K121701	0.64	1.86	0.30	†	†	†	†
	5	K121301	0.55	1.95	†	-0.21	-0.01	0.22	†
	6	K117601	0.86	1.67	0.34	†	†	†	†
	7	K120801	1.14	0.91	0.20	†	†	†	†
	8	K120802	0.30	1.72	†	-0.40	0.40	†	†
	17	K121201	0.96	-0.46	0.20	†	†	†	†
S6	1	K125101	0.37	-1.34	0.27	†	†	†	†
	7	K122101	0.39	1.38	†	0.72	1.51	0.05	-2.28
	14	K125401	0.46	1.40	†	1.28	-1.28	†	†
	15	K125402	0.46	0.33	†	0.56	-0.56	†	†
	17	K124401	1.08	0.18	0.33	†	†	†	†
S7	1	K111301	1.26	1.09	0.29	†	†	†	†
	4	K1107CL	0.54	-0.48	†	1.70	0.01	-1.71	†
	5	K114501	1.58	1.39	0.19	†	†	†	†
	7	K110602	0.74	0.22	0.26	†	†	†	†
	8	K110603	1.56	1.31	0.27	†	†	†	†
	10	K110401	0.40	1.09	†	-0.46	0.63	-0.17	†
S8	2	K112501	0.48	0.74	0.32	†	†	†	†
	4	K155501	1.12	0.43	0.17	†	†	†	†
	5	K155502	1.34	0.36	0.20	†	†	†	†
	12	K155751	0.58	1.61	†	0.48	-0.48	†	†
	13	K155752	0.42	1.35	†	-0.25	1.11	-0.86	†
S9	1	K115101	0.73	-0.51	0.21	†	†	†	†
	3	K115201	0.68	0.78	†	0.11	0.84	-0.95	†
	6	K156101	0.43	1.96	†	-1.95	1.99	-0.04	†
	7	K115501	1.65	1.51	0.17	†	†	†	†
	13	K111401	1.01	1.51	0.31	†	†	†	†
	14	K156201	1.16	0.68	0.41	†	†	†	†
S10	1	K168401	1.15	-0.18	0.46	†	†	†	†
	9	K168201	0.51	0.12	0.18	†	†	†	†
	11	K166901	0.65	-0.09	0.15	†	†	†	†
	13	K167301	0.81	0.13	0.28	†	†	†	†
	14	K167601	0.53	1.68	0.00	†	†	†	†
	15	K167701	0.45	0.09	†	-0.98	0.98	†	†
	16	K167101	1.35	0.08	0.20	†	†	†	†
S11	2	K169201	0.60	0.32	0.09	†	†	†	†
	4	K169701	0.28	1.42	†	-5.63	5.60	0.04	†
	5	K168101	0.94	-0.05	0.26	†	†	†	†
	7	K166501	0.94	0.62	0.20	†	†	†	†
	8	K168701	0.58	1.17	†	1.18	-1.18	†	†
	9	K166101	0.79	1.29	†	1.56	-1.56	†	†
	15	K171401	1.21	0.25	0.34	†	†	†	†
S12	1	K118001	0.78	-0.71	0.22	†	†	†	†
	3	K156901	1.30	1.49	0.26	†	†	†	†
	4	K118601	1.21	1.02	0.13	†	†	†	†
	5	K124001	0.72	0.15	0.26	†	†	†	†
	6	K116901	0.43	-0.57	†	-0.49	0.49	†	†
	10	K124301	0.37	1.55	0.10	†	†	†	†
	13	K118801	0.62	0.88	0.19	†	†	†	†
	14	K157101	0.89	0.94	0.32	†	†	†	†
	15	K115601	1.00	0.32	0.33	†	†	†	†
† 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_j_i represents the category threshold parameter for category i. The c parameter 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 Science Assessment.

Last updated 17 November 2021 (ML)

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