NAEP Analysis and Scaling - Overall Descriptive Statistics for Items as Defined After Scaling, Grade 8 Mathematics Combined National and State Main Assessment: 2007

NAEP Analysis and Scaling → Initial Activities → Classical Item Analysis → Overall Descriptive Statistics for Items as Defined After Scaling, Grade 8 Mathematics Combined National and State Main Assessment: 2007

NAEP Technical DocumentationOverall descriptive statistics for items as defined after scaling, grade 8 mathematics combined national and state main assessment: 2007
Statistic	Item type	Block M3	Block M4	Block M5	Block M6	Block M7	Block M8	Block M9	Block M10	Block M11	Block M12
† 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), 2007 Mathematics Assessment.
Number of scaled items	Total	15	14	18	16	16	18	18	16	19	17
	Multiple choice	11	11	9	13	12	12	10	13	16	14
	Dichotomously scored constructed response	2	0	3	1	2	2	2	2	3	1
	Polytomously scored constructed response	2	3	6	2	2	4	6	1	0	2
Unweighted sample size	†	30,400	30,400	30,500	30,500	30,700	30,800	30,500	30,600	30,600	30,500
Weighted average item score	†	0.46	0.44	0.61	0.51	0.51	0.54	0.48	0.52	0.55	0.49
Weighted average polyserial	†	0.63	0.64	0.62	0.64	0.58	0.60	0.59	0.61	0.58	0.59
Weighted alpha reliability	†	0.77	0.77	0.80	0.80	0.75	0.79	0.79	0.77	0.76	0.77
Weighted proportion of students attempting last item¹	†	0.92	0.95	0.88	0.94	0.77	0.87	0.79	0.98	0.95	0.97

Last updated 02 March 2010 (JL)