|Statistic||Type of school||All items|
|† Not applicable.
1 The "Weighted proportion of students attempting last item" is equal to 1 - (Percent not responding to last item /100).
NOTE: Nonpublic-school samples include only Catholic and private schools.
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||†||20|
|Unweighted sample size||Public||135,100|
|Weighted average item score||Public||0.55|
|Weighted average polyserial||Public||0.91|
|Weighted alpha reliability||Public||†|
|Weighted proportion of students attempting last item1||Public||†|