NAEP Technical DocumentationComparison of Means and Percentiles of 2013 Scores and 2013-Transformed Provisional Scores, Grade 8 Mathematics Combined National and State Assessment, by Scale: 2015

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. Prior to transformation, provisional estimates 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.

Comparison of means and percentiles of 2013 scores and 2013-transformed provisional scores, grade 8 mathematics combined national and state assessment, by scale: 2015

Scale	Statistic	Original 2013 estimate	2013-transformed provisional estimate	Difference between the provisional estimate and the original estimate
Composite	Mean	284.61	284.61	#
	10th percentile	237.40	235.29	-2.11
	25th percentile	260.78	259.64	-1.14
	50th percentile	285.60	285.63	0.03
	75th percentile	309.71	310.77	1.06
	90th percentile	330.62	332.50	1.88
Number properties and operations	Mean	280.75	280.75	#
	10th percentile	233.64	233.26	-0.39
	25th percentile	257.13	256.63	-0.50
	50th percentile	281.73	281.58	-0.15
	75th percentile	305.74	305.99	0.26
	90th percentile	326.70	327.09	0.39
Measurement	Mean	280.33	280.33	#
	10th percentile	219.95	219.43	-0.52
	25th percentile	250.56	249.82	-0.74
	50th percentile	282.07	281.82	-0.25
	75th percentile	312.17	312.53	0.37
	90th percentile	338.53	339.20	0.67
Geometry	Mean	282.19	282.19	#
	10th percentile	238.36	238.13	-0.24
	25th percentile	260.53	259.61	-0.92
	50th percentile	283.42	282.82	-0.60
	75th percentile	305.22	305.34	0.12
	90th percentile	324.46	325.38	0.92
Data analysis, statistics, and probability	Mean	286.19	286.19	#
	10th percentile	231.53	230.97	-0.55
	25th percentile	259.11	258.30	-0.81
	50th percentile	287.75	287.47	-0.28
	75th percentile	315.09	315.48	0.38
	90th percentile	338.94	339.68	0.74
Algebra	Mean	290.14	290.14	#
	10th percentile	241.36	241.20	-0.16
	25th percentile	265.72	265.22	-0.50
	50th percentile	291.39	291.11	-0.28
	75th percentile	316.09	316.23	0.13
	90th percentile	337.41	337.80	0.39
# Rounds to zero. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Mathematics Assessment.

Printer-friendly Version