NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → IRT Parameters for the Mathematics Long-Term Trend Assessments → IRT Parameters for Single Overall Scale, Age 9 Mathematics Long-Term Trend Assessment, by Item and Block: 2012

NAEP Technical DocumentationIRT parameters for single overall scale, age 9 mathematics long-term trend assessment, by item and block: 2012

Block	Item	NAEP ID	aj	bj	cj
† Not applicable; dichotomously scored constructed-response items use a 2 PL model, which does not include a c parameter. NOTE: For item j, aj represents the discriminatory power of the item, bj represents a location parameter related to item difficulty, and cj represents the guessing parameter. The c parameter value is exactly zero for items scaled with the two-parameter logistic model. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2012 Mathematics Long-Term Trend Assessment.
MA	1	N291601	0.87	-0.54	0.12
	2	N291701	0.81	-1.25	0.28
	3	N291801	1.83	1.90	0.14
	4	N291901	0.46	1.28	0.20
	5	N292001	0.63	-0.91	0.09
	6	N292101	1.08	-0.92	†
	7	N292201	0.75	0.63	0.16
	8	N292301	0.69	0.38	0.36
	9	N292401	0.60	-0.37	†
	10	N292501	1.49	0.96	0.43
	11	N292601	1.41	0.05	0.16
	12	N292701	0.97	-1.14	0.27
	13	N292801	0.79	-1.58	0.27
	14	N292901	1.46	-0.78	0.17
	15	N293001	0.85	-0.65	†
	16	N293101	1.16	-2.08	0.12
	17	N293201	1.28	0.60	0.18
	18	N293301	0.85	-1.06	†
	19	N293401	1.06	-1.16	0.22
	20	N293501	0.74	-0.86	†
	21	N293601	1.28	0.74	0.17
	22	N293701	1.72	0.13	0.11
	23	N293801	1.29	0.55	0.17
MA	1	N332001	0.86	-1.59	0.20
	2	N331101	1.06	-0.14	0.08
	3	N331301	0.49	-4.52	0.25
	4	N331701	1.20	-0.11	†
	5	N331702	0.87	0.40	0.25
	6	N330701	1.57	-0.63	0.25
	7	N329501	0.83	-0.21	†
	8	N358001	0.50	-0.53	0.30
	9	N331001	1.51	-0.25	0.28
	10	N329201	0.50	0.29	†
	11	N330001	0.34	-1.21	0.22
	12	N331501	0.66	0.32	†
	13	N332301	0.91	0.58	0.37
	14	N330601	1.17	0.33	0.15
	15	N329101	0.64	-1.08	†
	16	N331601	0.65	-2.14	†
	17	N332901	1.25	-0.39	0.30
	18	N331801	1.52	-0.18	0.15
	19	N331901	1.58	1.02	†
	20	N330101	0.65	1.24	0.22
	21	N330102	1.10	1.41	0.24
	22	N330901	1.08	0.18	0.19
	23	N332101	1.04	-0.04	†
	24	N328901	1.30	-0.45	0.12
MB	1	N293901	1.08	-1.62	0.09
	2	N294001	0.84	-2.69	0.11
	3	N294101	0.90	-1.48	0.32
	4	N294201	0.80	-2.81	†
	5	N294301	1.08	-0.99	†
	6	N294401	0.87	-0.79	0.18
	7	N294501	0.89	-0.72	0.12
	8	N294601	1.12	-0.14	0.17
	9	N294701	0.40	-2.79	0.13
	10	N294801	1.54	1.54	0.14
	11	N294901	0.81	0.17	0.30
	12	N295001	0.65	-2.19	0.16
	13	N295101	1.24	-0.25	0.22
	14	N295201	1.21	-0.28	0.21
	15	N295301	1.06	-1.22	†
	16	N295401	0.96	-0.60	†
	17	N295501	1.42	0.22	0.20
	18	N295601	0.88	-1.46	0.15
	19	N295701	1.17	0.61	†
	20	N295801	1.31	0.28	0.31
	21	N295901	1.34	1.13	0.07
	22	N296001	1.00	0.69	0.32
	23	N296101	1.01	0.77	0.23
MC	1	N322001	0.61	-3.06	0.24
	2	N322101	0.49	-0.55	0.21
	3	N322201	0.80	-0.74	0.13
	4	N322301	0.91	-1.23	0.37
	5	N322401	0.77	-0.22	†
	6	N322501	1.59	0.96	0.15
	7	N322601	0.82	-1.31	0.11
	8	N322602	1.13	1.45	0.09
	9	N322701	0.27	-0.01	0.21
	10	N322801	0.23	-3.70	0.26
	11	N322901	0.59	-0.65	0.25
	12	N323001	0.83	-0.98	0.10
	13	N323101	1.15	-0.27	†
	14	N323201	0.98	-1.57	0.23
	15	N323301	1.24	0.70	0.22
	16	N323401	0.96	-1.87	0.29
	17	N323501	0.69	1.19	0.38
	18	N323601	0.82	0.03	0.29
	19	N323701	0.93	-0.58	†
	20	N323801	1.27	0.55	0.15
	21	N323901	0.99	-0.67	†
	22	N324001	1.10	-0.56	†
MD	1	N312401	1.10	-2.01	0.13
	2	N312501	1.59	-0.62	0.25
	3	N312601	0.65	-1.53	0.24
	4	N312701	0.99	-1.96	0.29
	5	N312702	0.69	-2.31	0.20
	6	N312801	0.68	-1.88	0.34
	7	N312901	0.99	-1.28	†
	8	N313001	0.73	-1.37	†
	9	N313101	0.94	-0.95	†
	10	N313102	0.95	0.01	†
	11	N313103	0.91	-0.18	†
	12	N313201	0.49	-0.94	0.17
	13	N313301	1.20	-2.15	0.17
	14	N313302	0.53	-2.06	0.08
	15	N313303	0.99	-0.43	0.08
	16	N313401	0.75	-0.85	0.14
	17	N313501	0.57	-1.60	0.06
	18	N313502	1.02	0.17	0.13
	19	N313503	1.23	-0.72	0.09
	20	N313601	1.47	0.43	0.38
	21	N313701	1.03	-0.81	†
	22	N313702	1.18	0.43	†
	23	N313801	0.88	-0.53	†
	24	N313901	0.85	-0.84	†
	25	N314001	1.57	1.02	0.26
	26	N314101	1.00	1.50	0.09
ME	1	N287401	1.10	-0.08	0.14
	2	N287501	1.22	-0.84	0.08
	3	N287601	1.13	0.73	†
	4	N287701	0.76	-1.64	0.28
	5	N287801	0.79	-2.09	0.11
	6	N287901	0.68	-2.06	0.21
	7	N288001	1.17	-0.36	0.14
	8	N288101	0.66	-0.39	†
	9	N288201	1.45	1.14	0.28
	10	N288301	0.70	-1.92	0.15
	11	N288401	1.23	-0.40	0.41
	12	N288501	1.10	-0.61	†
	13	N288601	1.25	-0.15	0.10
	14	N288701	1.01	-1.43	0.25
	15	N288801	1.26	0.53	0.25
	16	N288901	0.92	-0.45	0.21
	17	N289001	1.16	0.43	0.17
	18	N289101	1.58	0.39	0.15
	19	N289201	1.23	-0.46	†
	20	N289301	1.20	1.55	0.26
	21	N289401	0.75	-0.18	0.36
MF	1	N289501	0.51	-1.66	0.27
	2	N289601	1.12	-0.84	0.52
	3	N289701	1.13	-0.78	†
	4	N289801	0.90	-1.58	0.23
	5	N289901	0.65	-2.08	†
	6	N290001	0.76	-0.94	0.27
	7	N290101	0.88	0.10	†
	8	N290201	1.16	-0.08	0.11
	9	N290301	2.23	1.49	0.14
	10	N290401	0.61	-0.58	0.09
	11	N290501	0.56	-1.39	0.33
	12	N290601	1.24	-0.18	0.43
	13	N290701	0.35	-3.75	†
	14	N290801	1.22	0.17	0.12
	16	N2909CL	0.52	3.72	†
	17	N291101	0.86	-0.15	0.32
	18	N291201	1.41	-0.19	0.17
	19	N291301	0.92	1.36	0.35
	20	N291401	0.70	-0.07	0.26
	21	N291501	0.48	1.74	†

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