NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Items as Defined After Scaling, Grade 4 Civics National Assessment: 2010

NAEP Technical DocumentationOverall descriptive statistics for items as defined after scaling, grade 4 civics national assessment: 2010

Statistic	Item type	Block C3	Block C4	Block C5	Block C6	Block C7	Block C8
† Not applicable. 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. The "weighted proportion of students attempting last item" is equal to 1 - (Percent not responding to last item /100). 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), 2010 Civics Assessment.
Number of scaled items	Total	15	15	15	14	15	15
	Multiple choice	11	11	12	10	11	12
	Dichtomously scored constructed response	0	1	0	1	0	0
	Polytomously scored constructed response	4	3	3	3	4	3
Unweighted sample size	†	2,400	2,400	2,300	2,400	2,400	2,300
Weighted average item score	†	.57	.48	.51	.59	.55	.60
Weighted average polyserial	†	.57	.53	.55	.54	.55	.51
Weighted alpha reliability	†	.75	.69	.72	.70	.75	.68
Weighted proportion of students attempting last item	†	.88	.91	.88	.89	.80	.91

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