NAEP Analysis and Scaling → Scale Linking and Transformation to the Reporting Metric → Comparisons of Distributions of Linking Samples for NAEP Assessments → Comparison of Means and Percentiles of 2007 Scores and 2007 Transformed Provisional Scores, Grade 8 Reading Combined National and State Main Assessment, by Scale: 2009

Original estimates are based on previous assessment data and previous assessment scaling results, transformed to the reporting metric using the transformation identified during the analysis of the previous assessment data. Provisional estimates are based on previous assessment data and current assessment scaling results. These are on the theta metric specified by the scaling program. The original and provisional estimates for the linking sample are used to find the transformation constants necessary to place the current assessment scale scores on the scale used to report previous assessment scale scores. The transformed provisional estimates are based on previous assessment data and current assessment scaling results, transformed to the reporting metric using the transformation constants calculated from the original and provisional estimates for the linking sample. If the transformation constants are correct, the original and transformed provisional means should be the same.

NAEP Technical DocumentationComparison of means and percentiles of 2007 scores and 2007 transformed provisional scores, grade 8 reading combined national and state main assessment, by scale: 2009

Scale	Statistics	Original 2007 estimate	2007-transformed provisional estimate	Difference between the provisional estimate and the original estimate
# Rounds to zero. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Reading Assessment.
Composite scale	Mean	262.79	262.79	#
	10th percentile	217.40	217.14	-0.26
	25th percentile	241.87	241.50	-0.37
	50th percentile	265.35	265.20	-0.15
	75th percentile	286.70	286.76	0.06
	90th percentile	304.73	305.12	0.39
Literary	Mean	261.81	261.81	#
	10th percentile	214.08	213.42	-0.66
	25th percentile	239.36	238.74	-0.62
	50th percentile	264.20	263.97	-0.23
	75th percentile	286.98	287.07	0.09
	90th percentile	306.33	306.88	0.55
Information	Mean	264.22	264.22	#
	10th percentile	217.33	216.97	-0.36
	25th percentile	242.36	242.07	-0.29
	50th percentile	266.65	266.69	0.04
	75th percentile	288.94	289.14	0.20
	90th percentile	308.00	308.27	0.27

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