NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Items as Defined After Scaling, Grade 8 Writing National Assessment, By Block: 2011

NAEP Technical DocumentationOverall descriptive statistics for items as defined after scaling, grade 8 writing national assessment, by block: 2011

Statistic	Item type	Block W
† 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), 2011 Writing Assessment.
Number of scaled items	Total	22
	Multiple choice	0
	Dichtomously scored constructed response	0
	Polytomously scored constructed response	22
Unweighted sample size	†	24,100
Weighted average item score	†	.48
Weighted average polyserial	†	.94
Weighted alpha reliability	†	†
Weighted proportion of students attempting last item	†	†

Printer-friendly Version