NAEP Technical DocumentationOverall Descriptive Statistics for Item Blocks as Defined After Scaling, Grade 8 Civics National Assessment, by Block: 2014

Overall descriptive statistics for item blocks as defined after scaling, grade 8 civics national assessment, by block: 2014

Statistic	Item type	Block C3	Block C4	Block C5	Block C6	Block C7	Block C8	Block C9	Block C10
Number of scaled items	Total	20	17	18	19	18	19	19	19
	Multiple choice	15	13	14	14	14	16	16	15
	Dichtomously scored constructed response	0	0	0	0	0	1	0	0
	Polytomously scored constructed response	5	4	4	5	4	2	3	4
Unweighted sample size	†	2,300	2,300	2,300	2,300	2,200	2,300	2,300	2,300
Weighted average item score	†	.56	.50	.46	.54	.49	.57	.52	.56
Weighted average polyserial	†	.50	.49	.54	.55	.49	.49	.55	.58
Weighted alpha reliability	†	.72	.68	.76	.78	.69	.69	.77	.81
Weighted proportion of students attempting last item1	†	.93	.87	.90	.89	.86	.93	.96	.91
† Not applicable. 1 The "Weighted proportion of students attempting last item" is equal to 1 – (Percent not responding to last item /100). NOTE: The "weighted average item score" of polytomous items are standardized to have a scale of 0 to 1 so they are comparable to dichotomously scored items. Item statistics in this table are described on the page Blocks of Items. In 2014, grades 4 and 12 were not assessed. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2014 Civics Assessment.

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