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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for the Life Science Scale, by Block and Item, Grade 4 Science National Main Assessment (Accommodations Permitted [R3]): 2000

NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 4 science national main assessment (accommodations permitted [R3]): 2000

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3
S3	2	K0310CL	0.14	1.04	0.00	-17.52	11.33	0.29
	3	K031003	0.46	2.85	0.00	1.81	-1.81	†
	4	K031004	0.58	-0.43	0.00	†	†	†
	5	K031005	0.43	1.89	0.00	0.89	-0.89	†
	6	K031006	0.56	0.04	0.00	0.40	-0.40	†
	7	K031007	0.43	0.78	0.00	0.00	-0.00	†
S8	1	K104201	0.52	-2.23	0.16	†	†	†
	2	K103301	0.72	2.65	0.20	†	†	†
	3	K103401	1.42	0.08	0.20	†	†	†
	4	K103601	1.41	0.03	0.21	†	†	†
	5	K103701	0.90	0.49	0.19	†	†	†
	6	K104001	1.18	-0.64	0.28	†	†	†
	8	K104301	1.24	0.64	0.32	†	†	†
	9	K103801	1.02	0.78	0.28	†	†	†
	10	K103901	0.37	1.87	0.00	†	†	†
	11	K104101	1.23	1.02	0.27	†	†	†
	12	K103001	0.84	1.13	0.14	†	†	†
	13	K103101	0.74	3.38	0.00	†	†	†
	14	K103201	0.15	4.79	0.24	†	†	†
	15	K102801	1.19	1.19	0.26	†	†	†
	16	K102901	1.34	1.03	0.28	†	†	†
S9	1	K031601	0.96	-0.08	0.28	†	†	†
	2	K031602	0.58	0.99	0.00	0.29	-0.29	†
	3	K031603	0.66	-0.54	0.00	†	†	†
	4	K031604	0.35	3.88	0.00	1.87	-1.87	†
	6	K031606	0.40	2.65	0.00	1.82	-1.82	†
	7	K031607	0.94	0.21	0.00	†	†	†
	8	K031608	0.56	3.04	0.00	2.27	-2.27	†
	9	K031609	0.61	2.09	0.00	-0.32	0.32	†
S10	1	K031701	0.69	-0.11	0.24	†	†	†
	9	K0325CL	0.43	-0.24	0.00	-0.33	-1.46	1.80
	10	K032601	0.86	1.26	0.00	0.85	-0.85	†
	11	K032602	0.77	1.37	0.00	†	†	†
S11	1	K099201	0.51	-1.66	0.31	†	†	†
	5	K098001	0.80	-0.78	0.28	†	†	†
	11	K092201	0.77	1.21	0.00	0.30	-0.30	†
S12	4	K033901	0.80	0.66	0.29	†	†	†
S13	1	K034601	0.37	0.22	0.25	†	†	†
	2	K034701	0.86	1.82	0.30	†	†	†
S14	2	K035501	0.40	-0.69	0.27	†	†	†
	6	K035901	0.65	2.14	0.00	†	†	†
S15	1	K037001	0.91	1.29	0.20	†	†	†
	2	K037101	0.45	-0.89	0.18	†	†	†
	3	K037201	1.04	0.92	0.27	†	†	†
S20	1	K099101	0.44	-1.25	0.31	†	†	†
	4	K090101	0.47	-1.69	0.22	†	†	†
	7	K098101	0.70	0.37	0.14	†	†	†
S21	5	K039901	0.43	-0.99	0.00	3.02	-0.92	-1.33
	8	K040201	1.28	1.65	0.14	†	†	†
† Not applicable; the number of item parameters estimated depends upon the IRT model used for scaling. 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 or the generalized partial credit model. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000 Science Assessment.

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