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

NAEP Technical DocumentationOverall Descriptive Statistics for Item Blocks as Defined After Scaling, Grade 8 Mathematics Combined National and State Assessment, by Block and Item Type: 2017

Overall descriptive statistics for item blocks as defined after scaling, grade 8 mathematics combined national and state assessment, by block and item type: 2017
Number of scaled items	Total	15	15	15	19	20	20	21	14	19	20
Statistic	Item type	Block M1	Block M2	Block M3	Block M4	Block M5	Block M6	Block M7	Block M8	Block M9	Block M10
	Multiple choice	4	3	2	15	16	16	17	1	14	16
	Dichotomously scored constructed-response	4	6	6	1	1	1	4	8	3	1
	Polytomously scored constructed-response	7	6	7	3	3	3	0	5	2	3
Unweighted sample size	†	28,000	28,000	28,400	28,100	28,000	28,100	27,900	30,600	31,200	31,000
Weighted average item score¹	†	.38	.43	.40	.42	.49	.47	.53	.34	.46	.54
Weighted average polyserial	†	.65	.65	.66	.62	.60	.57	.61	.70	.63	.64
Weighted alpha reliability	†	.77	.79	.78	.83	.82	.79	.82	.79	.83	.86
Weighted proportion of students attempting last item²	†	.78	.82	.79	.84	.88	.78	.91	.84	.85	.83
† Not applicable. ¹ 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. ²The "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 11 May 2022 (SK)

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