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

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

Block-level descriptive statistics as defined after scaling, grade 12 mathematics national assessment, by block and school type: 2015
Statistic	Type of school¹	Block M1	Block M2	Block M3	Block M4	Block M5	Block M6	Block M7	Block M8	Block M9	Block M10	Block M11	Block M12	Block M13	Block M14
Number of scaled items	†	14	14	14	14	14	14	13	13	13	13	14	14	14	13
Unweighted sample size	Public	1,682	1,650	1,691	1,647	1,664	1,688	1,770	1,769	1,731	1,764	1,704	1,706	1,668	1,703
Unweighted sample size	Nonpublic	186	191	179	179	189	176	167	170	172	179	167	181	184	195
Weighted average item score²	Public	.40	.44	.37	.36	.40	.41	.52	.38	.43	.39	.42	.38	.43	.38
Weighted average item score²	Nonpublic	.48	.54	.45	.45	.52	.52	.59	.48	.53	.47	.52	.46	.58	.43
Weighted average polyserial	Public	.62	.60	.63	.67	.63	.63	.61	.73	.67	.67	.62	.61	.62	.64
Weighted average polyserial	Nonpublic	.62	.63	.60	.67	.63	.63	.67	.74	.70	.65	.62	.64	.64	.65
Weighted alpha reliability	Public	.71	.74	.69	.78	.76	.73	.74	.81	.78	.76	.72	.68	.74	.73
Weighted alpha reliability	Nonpublic	.75	.77	.69	.78	.76	.72	.76	.82	.79	.76	.72	.74	.73	.76
Weighted proportion of students attempting last item³	Public	.81	.95	.70	.90	.96	.93	.98	.85	.95	.93	.95	.96	.97	.91
Weighted proportion of students attempting last item³	Nonpublic	.86	.95	.82	.90	.95	.96	1.00	.95	.95	.94	.98	.99	.99	.91
† 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), 2015 Mathematics Assessment.

Last updated 20 January 2022 (SK)

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