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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 13 Mathematics Long-Term Trend Assessment: 2008

Overall descriptive statistics for item blocks as defined after scaling, age 13 mathematics long-term trend assessment: 2008
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.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2008 Mathematics Long-Term Trend Assessment.
Number of scaled items    Total 23 23 27 37 23 23
Multiple choice 18 18 19 29 18 18
Dichotomously scored constructed response 5 5 8 8 5 5
Polytomously scored constructed response 0 0 0 0 0 0
Unweighted sample size 4,300 4,200 4,300 4,200 4,200 4,200
Weighted average item score 0.70 0.71 0.67 0.69 0.62 0.69
Weighted average polyserial 0.62 0.59 0.62 0.56 0.59 0.61
Weighted alpha reliability 0.83 0.80 0.88 0.87 0.82 0.82
Weighted proportion of students attempting last item1 0.98 0.95 0.85 0.74 0.94 0.97

Last updated 28 September 2011 (JL)