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

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 17 mathematics long-term trend assessment, by block: 2012

Statistic	Item type	Block M1	Block M2	Block M3	Block M4	Block M5	Block M6
† 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. Block M4 is an historical block. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2012 Mathematics Long-Term Trend Assessment.
Number of scaled items	Total	24	23	29	34	23	22
	Multiple choice	19	18	23	29	18	17
	Dichtomously scored constructed response	5	5	6	5	5	5
	Polytomously scored constructed response	0	0	0	0	0	0
Unweighted sample size	†	3,900	3,900	3,900	3,900	3,900	3,900
Weighted average item score	†	0.63	0.70	0.68	0.70	0.66	0.70
Weighted average polyserial	†	0.67	0.64	0.62	0.63	0.71	0.68
Weighted alpha reliability	†	0.87	0.82	0.87	0.89	0.88	0.85
Weighted proportion of students attempting last item1	†	0.85	0.96	0.81	0.73	0.92	0.97

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