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

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

Block	Item	NAEP ID	aj	bj	cj	dj1	dj2	dj3
† 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), 2012 Reading Long-Term Trend Assessment.
RA	1	N021101	1.69	0.05	0.25	†	†	†
	2	N021102	1.55	-0.28	0.35	†	†	†
	3	N021201	1.83	-0.04	0.31	†	†	†
	4	N021202	0.97	1.26	0.16	†	†	†
	5	N021203	0.49	1.54	†	0.99	-0.16	-0.83
	6	N021301	1.25	0.16	0.24	†	†	†
	7	N021302	1.96	0.93	0.09	†	†	†
	8	N021303	1.53	1.07	0.20	†	†	†
RB	1	N021401	0.53	-0.16	0.31	†	†	†
	2	N021402	0.75	0.49	0.19	†	†	†
	3	N021403	1.36	1.27	0.20	†	†	†
	4	N021501	1.59	-0.14	0.23	†	†	†
	5	N021502	1.09	0.27	0.25	†	†	†
	6	N021503	1.22	-0.45	0.24	†	†	†
	7	N021601	1.62	-0.21	0.30	†	†	†
	8	N021602	0.98	0.48	0.39	†	†	†
	9	N021603	0.91	0.78	0.20	†	†	†
	10	N021701	1.35	-0.95	0.26	†	†	†
RC	1	N021801	1.19	-0.08	0.34	†	†	†
	2	N021802	1.29	1.33	0.41	†	†	†
RC	3	N021803Y	0.43	0.65	†	2.56	-2.52	-0.03
RC	3	N021803Z	0.51	0.14	†	1.88	-1.88	†
RC	4	N021901	1.70	-0.60	0.31	†	†	†
	5	N022001	1.47	-0.14	0.24	†	†	†
	6	N022002	1.34	-0.47	0.23	†	†	†
	7	N022003	1.18	0.00	0.35	†	†	†
	8	N022004	2.14	-0.28	0.24	†	†	†
RD	1	N022101	1.80	-0.26	0.32	†	†	†
	2	N022102	1.95	1.00	0.18	†	†	†
	3	N022103	0.64	1.47	†	2.29	-0.14	-2.15
	4	N022201	1.32	0.97	0.39	†	†	†
	5	N022202	1.55	-0.59	0.27	†	†	†
	6	N022203	1.39	-0.04	0.22	†	†	†
	7	N022204	1.92	0.61	0.23	†	†	†
	8	N022205	1.76	0.45	0.18	†	†	†
RE	1	N022401	4.05	0.52	0.45	†	†	†
	2	N022402	2.51	0.59	0.22	†	†	†
	3	N022403	3.19	0.69	0.24	†	†	†
	4	N022404	5.03	0.75	0.16	†	†	†
	5	N022405	1.35	-0.07	0.00	†	†	†
	6	N022501	0.94	-0.25	0.36	†	†	†
	7	N022601	0.72	-0.69	0.31	†	†	†
RF	1	N022701	1.09	-0.55	0.36	†	†	†
	2	N022702	1.43	-0.30	0.24	†	†	†
	3	N022703	1.24	-0.98	0.37	†	†	†
	4	N022704	1.84	-0.42	0.22	†	†	†
	5	N022801	1.16	-2.05	0.25	†	†	†
	6	N022901	0.63	-1.81	0.22	†	†	†
	7	N023001	1.04	0.03	0.19	†	†	†
	8	N023002	1.35	0.60	0.28	†	†	†
	9	N023101	1.43	0.63	0.28	†	†	†
	10	N023102	1.14	0.50	0.25	†	†	†
RG	1	N023301	1.28	0.03	0.23	†	†	†
	2	N023401	0.73	-0.91	0.29	†	†	†
	3	N023402	1.70	0.22	0.31	†	†	†
	4	N023403	0.87	-0.56	0.25	†	†	†
	5	N023501	1.84	0.13	0.38	†	†	†
	6	N023502	1.23	-0.04	0.27	†	†	†
	7	N023601	1.51	-0.26	0.39	†	†	†
	8	N023602	0.90	-1.18	0.19	†	†	†
RH	1	N025901	0.98	-1.26	0.28	†	†	†
	2	N026001	2.13	-0.05	0.26	†	†	†
	3	N026002	1.28	-0.25	0.25	†	†	†
	4	N026003	1.63	-0.85	0.19	†	†	†
	5	N026101	1.21	0.61	0.13	†	†	†
	6	N026102	1.56	1.01	0.30	†	†	†
	7	N026201	1.15	-1.37	0.33	†	†	†
	8	N026301	1.73	-0.44	0.23	†	†	†
	9	N026302	0.91	-0.95	0.21	†	†	†
RH	1	N033801	0.62	-1.50	0.26	†	†	†
	2	N033803	0.81	-1.74	0.28	†	†	†
	3	N033901	0.93	-0.05	0.25	†	†	†
	4	N033902	1.46	-0.11	0.25	†	†	†
	5	N033903	1.89	0.11	0.15	†	†	†
	6	N030001	1.55	0.17	0.18	†	†	†
	7	N030002	1.61	-0.16	0.22	†	†	†
	8	N034101	1.77	-0.49	0.29	†	†	†
	9	N034102	1.91	-0.53	0.31	†	†	†
RI	1	N028601	1.39	-1.07	0.30	†	†	†
	2	N028602	1.47	-0.82	0.27	†	†	†
	3	N028701	1.74	-0.25	0.37	†	†	†
	4	N028702	1.42	-0.27	0.23	†	†	†
	5	N028703	1.04	-0.19	0.27	†	†	†
	6	N028704	1.67	-0.80	0.26	†	†	†
	7	N028801	1.21	0.19	0.20	†	†	†
	8	N028802	0.85	0.42	0.25	†	†	†
	9	N028901	1.06	0.29	0.29	†	†	†
	10	N028902	1.35	1.14	0.22	†	†	†
RJ	1	N026901	1.29	0.28	0.26	†	†	†
	2	N026902	1.54	-0.82	0.28	†	†	†
	3	N027001	1.33	-0.67	0.20	†	†	†
	4	N027002	1.11	-0.33	0.22	†	†	†
	5	N027003	0.99	-1.03	0.16	†	†	†
	6	N027101	1.54	0.05	0.25	†	†	†
	7	N027102	1.06	-0.06	0.30	†	†	†
	8	N027201	1.42	0.45	0.16	†	†	†
	9	N027202	1.63	-0.23	0.27	†	†	†
	10	N027203	2.18	0.42	0.24	†	†	†

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