NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Items as Defined After Scaling, Age 17 Reading Long-Term Trend Assessment, By Block: 2012

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 17 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	10	10	10	10	10	9	11	11	11	11
	Multiple choice	9	9	9	9	9	8	11	10	10	11
	Dichtomously scored constructed response	0	0	0	0	0	0	0	0	0	0
	Polytomously scored constructed response	1	1	1	1	1	1	0	1	1	0
Unweighted sample size	†	2,460	2,455	2,433	2,464	2,466	2,458	2,457	2,440	2,463	2,451
Weighted average item score	†	0.80	0.73	0.82	0.81	0.80	0.71	0.80	0.77	0.69	0.76
Weighted average polyserial	†	0.69	0.67	0.77	0.83	0.81	0.69	0.74	0.70	0.63	0.70
Weighted alpha reliability	†	0.53	0.66	0.60	0.68	0.74	0.64	0.65	0.72	0.67	0.71
Weighted proportion of students attempting last item1	†	0.96	0.91	0.98	0.99	0.97	0.95	0.98	0.89	0.88	0.96

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