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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Block-Level Descriptive Statistics as Defined After Scaling, Grade 8 Mathematics Combined National and State Assessment, by Block and School Type: 2017

NAEP Technical DocumentationBlock-Level Descriptive Statistics as Defined After Scaling, Grade 8 Mathematics Combined National and State Assessment, by Block and School Type: 2017

Block-level descriptive statistics as defined after scaling, grade 8 mathematics combined national and state assessment, by block and school type: 2017
Statistic	Type of school ¹	Block M1	Block M2	Block M3	Block M4	Block M5	Block M6	Block M7	Block M8	Block M9	Block M10
Number of scaled items	†	15	15	15	19	20	20	21	14	19	20
Unweighted sample size	Public	27,000	27,100	27,400	27,100	27,100	27,100	27,000	29,700	30,200	30,000
Unweighted sample size	Nonpublic	600	600	600	600	600	600	600	600	600	600
Weighted average item score ²	Public	.38	.43	.40	.42	.49	.46	.53	.34	.45	.53
Weighted average item score ²	Nonpublic	.40	.47	.45	.48	.54	.53	.57	.36	.51	.62
Weighted average polyserial	Public	.65	.65	.66	.62	.60	.57	.61	.71	.63	.64
Weighted average polyserial	Nonpublic	.59	.61	.62	.58	.58	.53	.58	.66	.60	.59
Weighted alpha reliability	Public	.77	.79	.78	.84	.82	.79	.82	.80	.83	.86
Weighted alpha reliability	Nonpublic	.73	.76	.76	.80	.79	.75	.80	.76	.80	.82
Weighted proportion of students attempting last item ³	Public	.77	.81	.79	.84	.88	.78	.90	.84	.85	.83
Weighted proportion of students attempting last item ³	Nonpublic	.86	.89	.80	.91	.95	.89	.95	.91	.91	.90
† 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: 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), 2017 Mathematics Assessment.

Last updated 04 August 2022 (ML)

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