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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 of Means and Percentiles of 2005 Scores and 2005 Transformed Provisional Scores, Grade 8 Mathematics Combined National and State Main Assessment, by Scale: 2007

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 2005 scores and 2005 transformed provisional scores, grade 8 mathematics combined national and state main assessment, by scale: 2007

Scale	Statistic	Original 2005 estimate	2005 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), 2007 Mathematics Assessment.
Composite scale	Mean	278.82	278.82	#
	10th percentile	231.47	229.91	1.56
	25th percentile	255.38	254.30	1.08
	50th percentile	280.21	280.05	0.16
	75th percentile	303.89	304.72	-0.83
	90th percentile	324.29	326.09	-1.80
Number Properties and Operations	Mean	277.58	277.58	#
	10th percentile	229.19	229.03	0.16
	25th percentile	254.11	253.47	0.64
	50th percentile	279.63	279.26	0.37
	75th percentile	303.17	303.30	-0.13
	90th percentile	323.01	323.75	-0.74
Measurement	Mean	275.76	275.76	#
	10th percentile	214.66	214.65	0.01
	25th percentile	245.98	245.00	0.98
	50th percentile	278.14	277.32	0.82
	75th percentile	308.06	308.06	0.00
	90th percentile	333.63	334.82	-1.19
Geometry	Mean	275.59	275.59	#
	10th percentile	231.55	231.34	0.21
	25th percentile	253.81	253.42	0.39
	50th percentile	276.94	276.61	0.33
	75th percentile	298.77	298.82	-0.05
	90th percentile	317.78	318.44	-0.66
Data Analysis and Probability	Mean	281.79	281.79	#
	10th percentile	227.98	227.54	0.44
	25th percentile	255.19	254.69	0.50
	50th percentile	283.54	283.41	0.13
	75th percentile	310.34	310.49	-0.15
	90th percentile	333.26	333.81	-0.55
Algebra	Mean	281.85	281.85	#
	10th percentile	234.62	234.55	0.07
	25th percentile	258.25	257.76	0.49
	50th percentile	282.86	282.49	0.37
	75th percentile	306.77	307.02	-0.25
	90th percentile	327.84	328.49	-0.65

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