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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 9 Mathematics Long-Term Trend Assessment: 2004

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 9 mathematics long-term trend assessment: 2004

Statistic	Item type	Block M21	Block M22	Block M23	Block M24	Block MX51	Block MX52
Number of scaled items	Total	23	23	24	26	21	20
	Multiple choice	18	18	15	17	17	14
	Dichotomously scored constructed response	5	5	9	9	4	6
	Polytomously scored constructed response	0	0	0	0	0	0
Unweighted sample size	†	3,700	3,700	3,700	3,700	3,600	3,700
Weighted average item score	†	0.61	0.66	0.67	0.71	0.63	0.61
Weighted average polyserial	†	0.61	0.65	0.61	0.67	0.64	0.57
Weighted alpha reliability	†	0.84	0.84	0.83	0.88	0.84	0.77
Weighted proportion of students attempting last item1	†	0.87	0.83	0.86	0.81	0.88	0.89
† 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), 2004 Mathematics Long-Term Trend Assessment.

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