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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: 2004
Overall descriptive statistics for item blocks as defined after scaling, age 17 reading long-term trend assessment: 2004
Statistic Item type Block R21 Block R22 Block R23 Block R24 Block R25 Block R26 Block R27 Block R28 Block R29 Block R30
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 2,500 2,400 2,500 2,500 2,500 2,500 2,400 2,500 2,500 2,500
Weighted average item score

0.78 0.71 0.80 0.80 0.80 0.69 0.79 0.76 0.75 0.74
Weighted average polyserial 0.72 0.67 0.80 0.83 0.82 0.70 0.75 0.72 0.75 0.71
Weighted alpha reliability 0.58 0.66 0.66 0.68 0.74 0.65 0.66 0.74 0.75 0.72
Weighted proportion of students attempting last item1 0.96 0.93 0.98 0.99 0.98 0.96 0.99 0.88 0.93 0.97
† 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 Long-Term Trend Reading Assessment.

Last updated 06 February 2009 (GF)

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