NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Items as Defined After Scaling, Age 9 Reading Long-Term Trend Assessment, By Block: 2012

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 9 reading long-term trend assessment, by block: 2012

Statistic	Item type	Block R1	Block R2	Block R3	Block R4	Block R5	Block R6	Block R7	Block R8	Block R9	Block R10
† Not applicable. 1 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), 2012 Reading Long-Term Trend Assessment.
Number of scaled items	Total	8	10	8	8	7	10	8	9	10	10
	Multiple choice	7	10	7	7	6	10	8	9	10	10
	Dichtomously scored constructed response	0	0	0	0	1	0	0	0	0	0
	Polytomously scored constructed response	1	0	1	1	0	0	0	0	0	0
Unweighted sample size	†	2,445	2,450	2,424	2,431	2,422	2,407	2,429	2,421	2,439	2,437
Weighted average item score	†	0.48	0.62	0.67	0.55	0.57	0.72	0.73	0.73	0.69	0.69
Weighted average polyserial	†	0.68	0.66	0.70	0.69	0.75	0.74	0.75	0.79	0.74	0.76
Weighted alpha reliability	†	0.63	0.68	0.68	0.69	0.70	0.70	0.68	0.76	0.72	0.77
Weighted proportion of students attempting last item1	†	0.84	0.96	0.90	0.87	0.88	0.96	0.98	0.94	0.94	0.97

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