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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Grade 12 U.S. History National Main Assessment: 2006
Overall descriptive statistics for item blocks as defined after scaling, grade 12 U.S. history national main assessment: 2006
Statistic Item type Block H3 Block H4 Block H5 Block H6 Block H7 Block H8 Block H9 Block H10 Block H11
Number of scaled items      Total 18 18 18 17 18 16 16 16 16
Multiple choice 13 13 13 12 13 12 12 11 6
Dichotomously scored constructed response 0 3 0 0 0 0 0 1 0
Polytomously scored constructed response 5 2 5 5 5 4 4 4 10
Unweighted sample size 2,300 2,300 2,300 2,200 2,200 2,300 2,300 2,300 2,200
Weighted average item score 0.47 0.42 0.48 0.43 0.45 0.47 0.57 0.50 0.58
Weighted average polyserial 0.53 0.59 0.53 0.57 0.50 0.57 0.57 0.56 0.67
Weighted alpha reliability 0.75 0.80 0.76 0.74 0.72 0.74 0.76 0.72 0.84
Weighted proportion of students attempting last item1 0.90 0.90 0.97 0.98 0.92 0.97 0.99 0.93 0.93
† 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), 2006 U.S. History Assessment.

Last updated 02 March 2010 (JL)

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