|Statistic||Item type||Block M21||Block M22||Block M23||Block M24||Block MX51||Block MX52|
|Number of scaled items||Total||23||22||37||36||23||22|
|Dichotomously scored constructed response||5||5||9||8||5||5|
|Polytomously scored constructed response||0||0||0||0||0||0|
|Unweighted sample size||†||3,800||3,700||3,800||3,700||3,700||3,700|
|Weighted average item score||†||0.69||0.72||0.69||0.68||0.60||0.66|
|Weighted average polyserial||†||0.61||0.62||0.58||0.58||0.59||0.63|
|Weighted alpha reliability||†||0.83||0.82||0.88||0.87||0.81||0.83|
|Weighted proportion of students attempting last item1||†||0.97||0.95||0.87||0.79||0.96||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 Mathematics Long-Term Trend Assessment.