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Table of Contents | Search Technical Documentation | References
HomeTDWNAEP Analysis and ScalingInitial ActivitiesClassical Item AnalysisBlock-Level Descriptive Statistics as Defined After Scaling, Grade 8 Vocabulary National Assessment, by Block and School Type: 2015
NAEP Technical DocumentationBlock-Level Descriptive Statistics as Defined After Scaling, Grade 8 Vocabulary National Assessment, by Block and School Type: 2015
| Statistic | Type of school1 | Block R14 | Block R15 | Block R16 | Block R17 | Block R18 | Block R19 | Embedded items |
|---|---|---|---|---|---|---|---|---|
| Number of scaled items | † | 6 | 5 | 5 | 5 | 6 | 6 | 24 |
| Unweighted sample size | Public | 2,400 | 3,000 | 3,000 | 2,400 | 2,400 | 2,400 | 4,000 |
| Nonpublic | 200 | 300 | 300 | 200 | 300 | 200 | 400 | |
| Weighted average item score2 | Public | .54 | .56 | .90 | .77 | .74 | .66 | .74 |
| Nonpublic | .61 | .67 | .97 | .89 | .85 | .75 | .83 | |
| Weighted average polyserial | Public | .67 | .73 | 1.19 | .91 | .82 | .76 | .64 |
| Nonpublic | .67 | .80 | 1.44 | 1.13 | .90 | .84 | .63 | |
|
Weighted alpha reliability | Public | .47 | .48 | .74 | .61 | .60 | .58 | † |
| Nonpublic | .43 | .54 | .57 | .58 | .50 | .64 | † | |
| Weighted proportion of students attempting last item3 | Public | .99 | .99 | 1.00 | .99 | .99 | .99 | † |
| Nonpublic | .99 | .99 | 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 column contains information about all the vocabulary items embedded in 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 21 July 2021 (SK)