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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Grade 8 Mathematics Combined National and State Main Assessment: 2005
Overall descriptive statistics for item blocks as defined after scaling, grade 8 mathematics combined national and state main assessment: 2005
Statistic Item type Block M3 Block M4 Block M5 Block M6 Block M7 Block M8 Block M9 Block M10 Block M11 Block M12
Number of scaled items Total 18 20 18 16 16 18 18 16 19 18
Multiple choice 12 7 9 13 12 12 10 13 16 15
Dichotomously scored constructed response 3 5 4 1 2 2 3 2 3 1
Polytomously scored constructed response 3 8 5 2 2 4 5 1 0 2
Unweighted sample size 32,300 32,100 32,200 32,300 32,600 32,400 32,100 32,300 32,100 32,300
Weighted average item score 0.54 0.61 0.59 0.49 0.50 0.53 0.48 0.51 0.54 0.56
Weighted average polyserial 0.60 0.62 0.61 0.63 0.58 0.60 0.59 0.61 0.57 0.55
Weighted alpha reliability 0.76 0.78 0.80 0.79 0.76 0.78 0.80 0.77 0.76 0.75
Weighted proportion of students attempting last item1 0.94 0.70 0.89 0.94 0.75 0.86 0.78 0.98 0.95 0.92
† 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), 2005 Mathematics Assessment.

Last updated 17 February 2010 (GF)

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