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 Scale, Grade 4 Science Combined National and State Main Assessment, by Item and Block: 2009

NAEP Technical DocumentationIRT parameters for items in the physical science scale, grade 4 science combined national and state main assessment, by item and block: 2009

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3	dj4
† 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 represents 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), 2009 Science Assessment.
S3	2	K080001	0.59	0.84	0.20	†	†	†	†
	5	K080301	0.44	0.16	0.16	†	†	†	†
	6	K080302	0.86	0.85	0.38	†	†	†	†
	7	K080404	0.66	1.15	†	0.79	-0.79	†	†
	16	K081001	1.30	0.33	0.22	†	†	†	†
	17	K081201	1.15	0.91	0.16	†	†	†	†
S4	4	K078902	0.58	1.53	†	2.47	-2.47	†	†
	11	K086401	0.62	-2.62	0.16	†	†	†	†
	12	K079801	1.67	1.12	0.15	†	†	†	†
S5	2	K081501	0.93	0.93	0.18	†	†	†	†
	5	K081801	0.44	1.58	†	0.26	-0.26	†	†
	7	K082101	3.05	1.34	0.16	†	†	†	†
	8	K082102	2.59	1.29	0.11	†	†	†	†
	9	K082103	0.49	1.90	0.29	†	†	†	†
	16	K084202	0.75	2.20	†	0.07	-0.07	†	†
	17	K084208	0.98	0.79	0.24	†	†	†	†
S6	2	K086501	1.55	1.08	0.41	†	†	†	†
	6	K107902	0.57	0.82	†	0.58	-0.58	†	†
	8	K0869CL	0.50	-0.86	†	1.07	-0.90	-0.17	†
	13	K109102	0.45	1.97	†	1.06	-1.06	†	†
	15	K087701	1.38	0.72	0.20	†	†	†	†
S7	6	K076601	0.54	-0.21	0.22	†	†	†	†
	10	K153601	0.77	0.36	†	0.16	-0.16	†	†
	11	K087101	0.82	0.86	†	-0.33	0.33	†	†
	12	K077001	1.38	1.20	0.23	†	†	†	†
	13	K077201	0.65	-0.38	†	0.11	-0.11	†	†
S8	3	K077501	0.45	-0.86	†	0.48	-0.48	†	†
	5	K106501	1.00	2.30	0.08	†	†	†	†
	7	K108501	1.22	1.49	0.23	†	†	†	†
	9	K078102	0.35	1.39	†	0.06	-1.80	1.75	†
	10	K078103	0.49	2.59	0.25	†	†	†	†
	15	K078301	0.55	0.59	†	0.80	-0.80	†	†
S9	7	K088401	0.56	1.67	†	2.00	0.85	0.52	-3.37
	10	K109401	0.40	-1.54	0.30	†	†	†	†
	11	K109402	0.80	1.58	†	-1.32	1.32	†	†
S10	2	K083701	0.73	0.04	0.17	†	†	†	†
	5	K154001	0.36	1.95	†	0.26	-0.26	†	†
	8	K083302	0.83	1.41	0.29	†	†	†	†
	12	K083601	0.52	-0.12	0.19	†	†	†	†
	13	K085301	1.14	0.87	0.16	†	†	†	†
	14	K085302	0.52	1.15	†	1.04	-1.04	†	†
S11	1	K089601	0.38	-2.03	0.17	†	†	†	†
	5	K088501	0.54	0.15	0.16	†	†	†	†
	6	K089701	0.89	0.06	0.29	†	†	†	†
	7	K089702	0.77	1.48	0.35	†	†	†	†
	13	K107601	0.84	1.44	0.21	†	†	†	†
	14	K080901	0.58	-1.21	†	†	†	†	†
	16	K107001	1.01	-0.77	0.17	†	†	†	†

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