NAEP Analysis and Scaling - Item-Level Descriptive Statistics as Defined After Scaling, Grade 8 Writing Combined National and State Main Assessment, by Public and Nonpublic School Sessions: 2007

NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Item-Level Descriptive Statistics as Defined After Scaling, Grade 8 Writing Combined National and State Main Assessment, by Public and Nonpublic School Sessions: 2007

NAEP Technical DocumentationItem-level descriptive statistics as defined after scaling, grade 8 writing combined national and state main assessment, by public and nonpublic school sessions: 2007
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
Unweighted sample size	Nonpublic	3,100
Weighted average item score	Public	0.55
Weighted average item score	Nonpublic	0.63
Weighted average polyserial	Public	0.91
Weighted average polyserial	Nonpublic	0.90
Weighted alpha reliability	Public	†
Weighted alpha reliability	Nonpublic	†
Weighted proportion of students attempting last item¹	Public	†
Weighted proportion of students attempting last item¹	Nonpublic	†

Last updated 07 June 2010 (JL)