|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||29||35||23||23|
|Dichotomously scored constructed response||4||5||6||5||5||5|
|Polytomously scored constructed response||0||0||0||0||0||0|
|Unweighted sample size||†||4,800||4,800||4,800||4,800||4,700||4,800|
|Weighted average item score||†||0.68||0.70||0.67||0.70||0.66||0.68|
|Weighted average polyserial||†||0.72||0.62||0.63||0.61||0.69||0.64|
|Weighted alpha reliability||†||0.89||0.81||0.87||0.89||0.87||0.84|
|Weighted proportion of students attempting last item1||†||0.92||0.97||0.81||0.72||0.93||0.98|