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Statistic | Item type | Block M3 | Block M4 | Block M5 | Block M6 | Block M7 | Block M8 | Block M9 | Block M10 | Block M11 | Block M12 |
---|---|---|---|---|---|---|---|---|---|---|---|
Number of scaled items | Total | 15 | 15 | 15 | 15 | 16 | 15 | 15 | 15 | 16 | 13 |
Multiple choice | 11 | 11 | 10 | 10 | 11 | 11 | 10 | 11 | 10 | 10 | |
Dichotomously scored constructed-response | 2 | 1 | 3 | 1 | 2 | 3 | 2 | 0 | 1 | 0 | |
Polytomously scored constructed-response | 2 | 3 | 2 | 4 | 3 | 1 | 3 | 4 | 5 | 3 | |
Unweighted sample size | † | 27,700 | 27,600 | 27,500 | 27,700 | 28,900 | 28,800 | 27,500 | 27,400 | 27,500 | 29,000 |
Weighted average item score1 | † | .56 | .51 | .63 | .52 | .57 | .60 | .56 | .55 | .54 | .59 |
Weighted average polyserial | † | .60 | .60 | .64 | .57 | .63 | .63 | .62 | .58 | .54 | .64 |
Weighted alpha reliability | † | .73 | .75 | .79 | .72 | .79 | .77 | .76 | .70 | .69 | .75 |
Weighted proportion of students attempting last item2 | † | .92 | .89 | .88 | .90 | .75 | .87 | .92 | .96 | .93 | .96 |
† Not applicable. 1 The "Weighted average item score" of polytomous items is standardized to have a scale of 0 to 1 so they are comparable to dichotomously scored items. 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), 2015 Mathematics Assessment. |