|Statistic||Item type||All items|
|† Not applicable.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2007 Writing Assessment.
|Number of scaled Items||Total||20|
|Dichotomously scored constructed response||0|
|Polytomously scored constructed response||20|
|Unweighted sample size||139,900|
|Weighted average iem score||0.55|
|Weighted average polyserial||0.92|
|Weighted alpha reliability||†|
|Weighted proportion of students attempting last item||†|