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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 17 Reading Long-Term Trend Assessment: 2008

Overall descriptive statistics for item blocks as defined after scaling, age 17 reading long-term trend assessment: 2008
Statistic Item type Block R21 Block R22 Block R23 Block R24 Block R25 Block R26 Block R27 Block R28 Block R29 Block R30
† 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 Reading Long-Term Trend Assessment.
Number of scaled items    Total 10 10 10 10 10 9 11 11 11 11
Multiple choice 9 9 9 9 9 8 11 10 10 11
Dichotomously scored constructed response 0 0 0 0 0 0 0 0 0 0
Polytomously scored constructed response 1 1 1 1 1 1 0 1 1 0
Unweighted sample size 2,900 2,900 2,900 2,900 2,900 2,900 2,800 2,900 2,900 2,900
Weighted average item score 0.78 0.72 0.82 0.79 0.80 0.70 0.81 0.78 0.68 0.76
Weighted average polyserial 0.70 0.69 0.80 0.82 0.83 0.68 0.76 0.73 0.64 0.71
Weighted alpha reliability 0.57 0.66 0.61 0.69 0.74 0.64 0.66 0.73 0.67 0.70
Weighted proportion of students attempting last item1 0.96 0.92 0.99 0.99 0.98 0.96 0.99 0.87 0.90 0.97

Last updated 28 September 2011 (JL)
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National Center for Education Statistics - http://nces.ed.gov
U.S. Department of Education