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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Block-Level Descriptive Statistics as Defined After Scaling, Grade 12 Vocabulary National Assessment, by Block and School Type: 2015

NAEP Technical DocumentationBlock-Level Descriptive Statistics as Defined After Scaling, Grade 12 Vocabulary National Assessment, by Block and School Type: 2015

Block-level descriptive statistics as defined after scaling, grade 12 vocabulary national assessment, by block and school type: 2015
Statistic	Type of school¹	Block R14	Block R15	Block R16	Block R17	Embedded items
Number of scaled items	†	6	5	6	5	27
Unweighted sample size	Public	2,700	2,700	2,300	2,300	2,200
Unweighted sample size	Nonpublic	300	300	200	200	200
Weighted average item score²	Public	.64	.66	.73	.63	.69
Weighted average item score²	Nonpublic	.73	.75	.82	.72	.77
Weighted average polyserial	Public	.74	.78	.84	.77	.64
Weighted average polyserial	Nonpublic	.83	.84	.96	.82	.67
Weighted alpha reliability	Public	.57	.53	.69	.52	†
Weighted alpha reliability	Nonpublic	.63	.51	.72	.54	†
Weighted proportion of students attempting last item³	Public	1.00	.99	1.00	.99	†
Weighted proportion of students attempting last item³	Nonpublic	1.00	1.00	1.00	.99	†
† Not applicable. ¹ Nonpublic 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: The embedded items column contains information about all the vocabulary items embedded within the 25-minute reading comprehension blocks. 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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