NAEP Analysis and Scaling - Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 9 Mathematics Long-Term Trend Assessment: 2008

NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 9 Mathematics Long-Term Trend Assessment: 2008

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 9 mathematics long-term trend assessment: 2008
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
	Multiple choice	18	18	17	17	17	14
	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

Last updated 28 September 2011 (JL)