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NAEP Analysis and Scaling → Scale Linking and Transformation to the Reporting Metric → Comparisons of Distributions of Linking Samples for NAEP Assessments → Comparison Means and Percentiles of Original 1999 Scores and 1999 Transformed Provisional Scores, Age 9 Reading Long-Term Trend Assessment: 2004

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 means and percentiles of original 1999 scores and 1999 transformed provisional scores, age 9 reading long-term trend assessment: 2004

Statistic	Original 1999 score	1999 transformed provisional score	Difference between the provisional score and the original score
Mean	211.75	211.75	#
10th percentile	158.23	158.76	0.53
25th percentile	185.03	185.07	0.04
50th percentile	214.83	213.90	-0.93
75th percentile	239.41	239.53	0.12
90th percentile	259.34	260.53	1.19
# Rounds to zero. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2004 Reading Long-Term Trend Assessment.

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