Statistic | Item type | Block M1 | Block M2 | Block M3 | Block M4 | Block M5 | Block M6 |
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† 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. |
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Number of scaled items | Total | 23 | 23 | 22 | 26 | 21 | 20 |
Multiple choice | 18 | 18 | 17 | 17 | 17 | 14 | |
Dichotomously scored constructed response | 5 | 5 | 5 | 9 | 4 | 6 | |
Polytomously scored constructed response | 0 | 0 | 0 | 0 | 0 | 0 | |
Unweighted sample size | † | 4,400 | 4,300 | 4,400 | 4,300 | 4,200 | 4,200 |
Weighted average item score | † | 0.64 | 0.68 | 0.66 | 0.72 | 0.65 | 0.63 |
Weighted average polyserial | † | 0.62 | 0.65 | 0.60 | 0.66 | 0.65 | 0.57 |
Weighted alpha reliability | † | 0.83 | 0.84 | 0.81 | 0.87 | 0.85 | 0.77 |
Weighted proportion of students attempting last item1 | † | 0.86 | 0.85 | 0.89 | 0.83 | 0.88 | 0.89 |