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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 State Assessment (Accommodations Not Permitted [R2]): 2000

NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 4 science state assessment (accommodations not permitted [R2]): 2000

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3
S3	2	K0310CL	0.14	1.00	0.00	-16.52	10.67	0.13
	3	K031003	0.47	2.81	0.00	1.79	-1.79	†
	4	K031004	0.59	-0.42	0.00	†	†	†
	5	K031005	0.43	1.88	0.00	0.86	-0.86	†
	6	K031006	0.56	0.04	0.00	0.39	-0.39	†
	7	K031007	0.45	0.78	0.00	0.02	-0.02	†
S8	1	K104201	0.51	-2.26	0.18	†	†	†
	2	K103301	1.01	2.40	0.22	†	†	†
	3	K103401	1.40	0.06	0.20	†	†	†
	4	K103601	1.39	-0.01	0.20	†	†	†
	5	K103701	0.88	0.48	0.19	†	†	†
	6	K104001	1.16	-0.62	0.31	†	†	†
	8	K104301	1.26	0.64	0.33	†	†	†
	9	K103801	1.06	0.75	0.28	†	†	†
	10	K103901	0.40	1.78	0.00	†	†	†
	11	K104101	1.19	1.00	0.26	†	†	†
	12	K103001	0.81	1.10	0.12	†	†	†
	13	K103101	0.72	3.40	0.00	†	†	†
	14	K103201	0.17	4.61	0.25	†	†	†
	15	K102801	1.23	1.18	0.26	†	†	†
	16	K102901	1.37	1.03	0.29	†	†	†
S9	1	K031601	1.03	-0.00	0.31	†	†	†
	2	K031602	0.57	0.98	0.00	0.29	-0.29	†
	3	K031603	0.49	-1.22	0.00	0.09	-0.09	†
	4	K031604	0.37	3.72	0.00	1.78	-1.78	†
	6	K031606	0.39	2.65	0.00	1.84	-1.84	†
	7	K031607	0.97	0.19	0.00	†	†	†
	8	K031608	0.55	3.17	0.00	2.40	-2.40	†
	9	K031609	0.61	2.08	0.00	-0.35	0.35	†
S10	1	K031701	0.67	-0.12	0.24	†	†	†
	9	K0325CL	0.42	-0.27	0.00	-0.43	-1.51	1.93
	10	K032601	0.85	1.27	0.00	0.87	-0.87	†
	11	K032602	0.73	1.42	0.00	†	†	†
S11	1	K099201	0.52	-1.69	0.30	†	†	†
	5	K098001	0.80	-0.82	0.28	†	†	†
	11	K092201	0.78	1.18	0.00	0.30	-0.30	†
S12	4	K033901	0.82	0.71	0.30	†	†	†
S13	1	K034601	0.35	0.42	0.29	†	†	†
	2	K034701	0.81	1.78	0.29	†	†	†
S14	2	K035501	0.39	-0.73	0.28	†	†	†
	6	K035901	0.61	2.21	0.00	†	†	†
S15	1	K037001	0.86	1.24	0.19	†	†	†
	2	K037101	0.44	-0.94	0.18	†	†	†
	3	K037201	1.10	0.92	0.28	†	†	†
S20	1	K099101	0.43	-1.37	0.29	†	†	†
	4	K090101	0.45	-1.74	0.23	†	†	†
† 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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