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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 Physical Science Subscale, Grade 8 Science Combined National and State Assessment, by Item and Block: 2015

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

IRT parameters for items in the physical science 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	4	K114001	0.99	0.15	0.34	†	†	†	†
	5	K114002	0.77	0.41	0.19	†	†	†	†
	7	K113201	0.31	-0.66	†	2.70	-2.09	-0.61	†
	11	K113603	0.40	0.67	0.08	†	†	†	†
	15	K134201	0.44	-0.11	†	-0.23	-0.31	0.55	†
S4	2	K114601	0.45	0.08	†	-0.21	0.35	-0.08	-0.07
	8	K116701	1.45	0.99	0.29	†	†	†	†
	10	K118901	1.00	-0.87	0.30	†	†	†	†
	11	K122402	0.30	1.80	†	-0.71	2.28	-1.57	†
	14	K122001	1.42	0.65	0.28	†	†	†	†
S5	2	K120601	1.78	1.51	0.30	†	†	†	†
	11	K120901	0.95	0.55	0.24	†	†	†	†
	12	K121401	1.48	0.63	0.41	†	†	†	†
	13	K121402	1.16	0.15	0.37	†	†	†	†
	14	K121403	2.75	1.32	0.10	†	†	†	†
S6	3	K124601	0.75	1.85	0.32	†	†	†	†
	6	K154901	0.71	0.66	0.27	†	†	†	†
	8	K125001	0.87	1.35	0.30	†	†	†	†
	9	K125002	0.93	0.84	0.31	†	†	†	†
	10	K125003	0.32	0.85	†	0.90	-0.90	†	†
	12	K155101	1.65	1.33	0.24	†	†	†	†
	13	K155201	0.88	0.22	0.25	†	†	†	†
S7	3	K155401	0.70	0.03	0.21	†	†	†	†
	9	K123901	0.40	0.75	†	1.23	1.82	-0.29	-2.77
	15	K110801	1.40	1.36	0.26	†	†	†	†
	16	K110101	1.29	1.33	0.34	†	†	†	†
S8	3	K111901	0.73	1.66	0.43	†	†	†	†
	6	K112401	0.55	1.30	†	-0.53	-2.51	3.03	†
	9	K155601	0.27	2.54	†	-1.71	1.55	1.70	-1.54
	10	K117201	0.86	0.40	0.42	†	†	†	†
	11	K117202	0.57	-0.27	0.00	†	†	†	†
	15	K112901	0.60	1.50	0.20	†	†	†	†
	17	K112701	0.54	0.11	0.19	†	†	†	†
S9	4	K114901	1.61	0.54	0.28	†	†	†	†
	5	K1560CL	0.24	1.82	†	0.96	-0.71	-0.25	†
	10	K115301	1.47	-0.05	0.45	†	†	†	†
S10	3	K168301	0.99	0.79	0.27	†	†	†	†
	4	K167801	0.71	-0.33	0.10	†	†	†	†
	5	K167901	0.69	-0.15	0.07	†	†	†	†
	7	K166701	0.61	0.46	0.35	†	†	†	†
	12	K165601	1.00	1.09	0.26	†	†	†	†
S11	3	K167501	0.43	-1.56	0.19	†	†	†	†
	10	K167201	0.35	-0.18	0.18	†	†	†	†
	12	K167001	0.75	-0.75	0.21	†	†	†	†
	13	K171201	1.69	-0.49	0.27	†	†	†	†
	14	K171301	0.63	0.45	†	-0.50	0.50	†	†
	16	K170601	0.81	1.18	0.25	†	†	†	†
S12	2	K156801	1.22	0.55	0.15	†	†	†	†
	8	K157001	0.59	1.02	†	1.17	-1.17	†	†
	9	K119505	0.74	1.08	†	0.69	-0.69	†	†
	11	K123401	0.60	0.40	†	0.28	-0.44	0.16	†
† 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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