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 2009 Scores and 2009 Transformed Provisional Scores, Grade 8 Science Combined National and State Main Assessments, By Scale: 2011

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 2009 scores and 2009 transformed provisional scores, grade 8 science combined national and state assessments, by scale: 2011

Scale	Statistics	Original 2009 estimate	2009-transformed provisional estimate	Difference between the provisional estimate and the original estimate
# Rounds to zero. NOTE: Single overall scale. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2011 Science Assessment.
Univariate scale	Mean	150.00	150.00	#
	10th percentile	103.22	103.10	-0.12
	25th percentile	128.39	127.91	-0.49
	50th percentile	153.23	153.00	-0.23
	75th percentile	174.83	174.97	0.15
	90th percentile	192.20	192.51	0.30

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