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 2008 Scores and 2008 Transformed Provisional Scores, Age 17 Reading Long-Term Trend Assessment, By Scale: 2012

Original estimates are based on previous assessment data and previous assessment scaling results, transformed to the reporting metric using the transformation constants 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 means and percentiles of 2008 scores and 2008 transformed provisional scores, age 17 reading long-term trend assessment, by scale: 2012

Scale	Statistics	Original 2008 estimate	2008-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), 2008 and 2012 Reading Long-Term Trend Assessments.
Composite scale	Mean	285.84	285.84	#
	10th percentile	227.42	227.59	0.17
	25th percentile	258.39	258.37	-0.02
	50th percentile	288.09	287.99	-0.10
	75th percentile	316.64	316.36	-0.28
	90th percentile	340.84	340.94	0.10

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