|Statistic||Item type||Block M1||Block M2||Block M3||Block M4||Block M5||Block M6|
|† 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.
|Number of scaled items||Total||23||23||22||26||21||20|
|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|