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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 Science State Assessment (Accommodations Permitted [R3]): 2000
Overall descriptive statistics for item blocks as defined after scaling, grade 8 science state assessment (accommodations permitted [R3]): 2000
Statistic Item type Block S3 Block S5 Block S6 Block S7 Block S8 Block S9 Block S10 Block S11 Block S12 Block S13 Block S14 Block S15 Block S20 Block S21
Number of scaled items Total 6 8 6 20 10 13 20 16 16 15 16 15 20 16
Multiple choice 0 0 0 14 5 3 14 8 8 8 7 6 14 7
Dichotomously scored constructed response 3 3 4 3 1 4 2 3 3 1 3 2 1 3
Polytomously scored constructed response 3 5 2 3 4 6 4 5 5 6 6 7 5 6
Unweighted sample size 14,200 14,300 14,500 19,400 19,500 19,300 14,600 14,600 14,600 14,700 19,500 14,600 14,500 14,400
Weighted average item score 0.49 0.41 0.29 0.44 0.56 0.51 0.48 0.45 0.33 0.39 0.46 0.36 0.42 0.43
Weighted average polyserial 0.73 0.77 0.76 0.49 0.70 0.58 0.54 0.53 0.54 0.50 0.56 0.56 0.49 0.52
Weighted alpha reliability 0.71 0.71 0.41 0.69 0.68 0.69 0.76 0.71 0.70 0.64 0.73 0.70 0.69 0.71
Weighted proportion of students attempting last item1 0.78 0.52 0.81 0.83 0.97 0.95 0.98 0.84 0.84 0.92 0.97 0.87 0.99 0.90
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), 2000 Science Assessment.

Last updated 17 March 2008 (GF)

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