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NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Block-Level Descriptive Statistics by Public- and Nonpublic-School Sessions, as Defined After Scaling, Grade 8 Science National Main Assessment (Accommodations Permitted [R3]): 2000
Block-level descriptive statistics by public- and nonpublic-school sessions, as defined after scaling, grade 8 science national main assessment (accommodations permitted [R3]): 2000
Statistic Type of school1 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 6 8 6 20 10 13 20 16 16 15 16 15 20 16
Unweighted sample size Public 1,500 1,500 1,500 2,100 2,100 2,100 1,600 1,500 1,600 1,600 2,100 1,600 1,600 1,500
Nonpublic 1,000 1,000 1,000 1,400 1,300 1,500 1,000 1,000 1,000 1,000 1,300 1,100 1,100 1,100
Weighted average item score Public 0.47 0.38 0.29 0.44 0.56 0.50 0.48 0.45 0.33 0.39 0.46 0.35 0.42 0.43
Nonpublic 0.55 0.46 0.34 0.51 0.63 0.56 0.56 0.52 0.41 0.45 0.51 0.41 0.47 0.49
Weighted alpha reliability Public 0.74 0.71 0.39 0.70 0.68 0.69 0.77 0.74 0.71 0.68 0.72 0.69 0.70 0.72
Nonpublic 0.65 0.71 0.38 0.67 0.55 0.62 0.72 0.69 0.68 0.60 0.68 0.64 0.68 0.64
Weighted average polyserial Public 0.75 0.76 0.76 0.50 0.69 0.58 0.54 0.55 0.55 0.52 0.56 0.55 0.49 0.52
Nonpublic 0.70 0.73 0.70 0.49 0.64 0.56 0.51 0.52 0.52 0.48 0.52 0.51 0.48 0.49
Weighted proportion of students attempting last item2 Public 0.74 0.49 0.78 0.80 0.96 0.93 0.97 0.82 0.79 0.90 0.97 0.85 0.98 0.87
Nonpublic 0.84 0.52 0.85 0.89 0.98 0.98 1.00 0.91 0.88 0.97 0.96 0.92 0.99 0.94
† Not applicable.
1 Nonpublic-school sample includes only Catholic and private schools.
2 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 10 July 2008 (GF)

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