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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Block-Level Descriptive Statistics as Defined After Scaling, Grade 8 Reading Combined National and State Assessment, by Block and School Type: 2015

NAEP Technical DocumentationBlock-Level Descriptive Statistics as Defined After Scaling, Grade 8 Reading Combined National and State Assessment, by Block and School Type: 2015

Block-level descriptive statistics as defined after scaling, grade 8 reading combined national and state assessment, by block and school type: 2015
Statistic	Type of school¹	Block R1	Block R2	Block R3	Block R4	Block R5	Block R6	Block R7	Block R8	Block R9	Block R10	Block R11	Block R12	Block R13
Number of scaled items	†	10	10	10	10	10	10	10	10	10	10	11	10	10
Unweighted sample size	Public	20,300	20,100	20,300	20,300	20,400	20,200	20,300	20,200	20,200	20,300	20,200	20,200	20,200
Unweighted sample size	Nonpublic	400	400	400	400	400	400	400	400	400	400	400	400	400
Weighted average item score²	Public	.64	.65	.60	.48	.77	.73	.76	.74	.67	.62	.68	.64	.63
Weighted average item score²	Nonpublic	.73	.73	.69	.59	.84	.82	.81	.83	.75	.71	.78	.72	.72
Weighted average polyserial	Public	.64	.65	.63	.63	.74	.73	.73	.78	.67	.66	.66	.66	.69
Weighted average polyserial	Nonpublic	.60	.66	.64	.63	.76	.74	.73	.78	.63	.62	.67	.62	.62
Weighted alpha reliability	Public	.72	.73	.67	.71	.73	.74	.68	.75	.72	.72	.76	.73	.72
Weighted alpha reliability	Nonpublic	.66	.67	.63	.67	.62	.66	.60	.65	.61	.62	.68	.67	.62
Weighted proportion of students attempting last item³	Public	.82	.89	.94	.71	.97	.95	.93	.95	.93	.92	.91	.76	.92
Weighted proportion of students attempting last item³	Nonpublic	.90	.96	.97	.84	1.00	.98	.98	.97	.98	.96	.95	.88	.96
† Not applicable. ¹Nonpublic school sample includes only private schools, including Catholic schools. BIE and DoDEA schools are not included in either the public or nonpublic category. ² The "Weighted average item score" of polytomous items is standardized to have a scale of 0 to 1 so they are comparable to dichotomously scored items. ³ The "Weighted proportion of students attempting last item" is equal to 1 – (Percent not responding to last item / 100). NOTE: Item statistics in this table are described on the page Blocks of Items. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Reading Assessment.

Last updated 09 November 2021 (ML)

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