NAEP Analysis and Scaling - Overall Descriptive Statistics for Item Blocks as Defined After Scaling, Age 17 Reading 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 17 Reading Long-Term Trend Assessment: 2008

NAEP Technical DocumentationOverall descriptive statistics for item blocks as defined after scaling, age 17 reading long-term trend assessment: 2008
Statistic	Item type	Block R21	Block R22	Block R23	Block R24	Block R25	Block R26	Block R27	Block R28	Block R29	Block R30
† 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 Reading Long-Term Trend Assessment.
Number of scaled items	Total	10	10	10	10	10	9	11	11	11	11
	Multiple choice	9	9	9	9	9	8	11	10	10	11
	Dichotomously scored constructed response	0	0	0	0	0	0	0	0	0	0
	Polytomously scored constructed response	1	1	1	1	1	1	0	1	1	0
Unweighted sample size	†	2,900	2,900	2,900	2,900	2,900	2,900	2,800	2,900	2,900	2,900
Weighted average item score	†	0.78	0.72	0.82	0.79	0.80	0.70	0.81	0.78	0.68	0.76
Weighted average polyserial	†	0.70	0.69	0.80	0.82	0.83	0.68	0.76	0.73	0.64	0.71
Weighted alpha reliability	†	0.57	0.66	0.61	0.69	0.74	0.64	0.66	0.73	0.67	0.70
Weighted proportion of students attempting last item¹	†	0.96	0.92	0.99	0.99	0.98	0.96	0.99	0.87	0.90	0.97

Last updated 28 September 2011 (JL)