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NAEP Analysis and Scaling → Estimation of Population and Student Group Distributions → Examining the Population-Structure Models Used in NAEP → Proportion of Variance of the Group-Defining Contrasts Accounted for by the Principal Components Used in NAEP Student Group Distribution Models → Proportion of Variance of the Group-Defining Contrasts Accounted for by the Principal Components Used in the Population-Structure Model, Age 9 Mathematics Long-Term Trend Assessment: 2004

NAEP Technical DocumentationProportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, age 9 mathematics long-term trend assessment: 2004
Type of contrast Number of contrasts Mean Minimum Maximum Number of contrasts by proportion1 of variance explained
0.00 - 0.70 0.71 - 0.80 0.81 - 0.90 0.91 - 0.95 0.96 - 1.00
1(Total Variance – Residual Variance)/Total Variance, where Total Variance consists of both sampling and measurement error variance.
NOTE: Teacher and school questionnaires were not included in the long-term trend assessments in 2004.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2004 Mathematics Long-Term Trend Assessment.
All contrasts 663 0.90 0.58 0.98 4 28 249 294 88
Student questionnaire 51 0.86 0.61 0.97 2 9 19 18 3
Major reporting variables 39 0.90 0.58 0.97 1 2 14 11 11
Interactions between reporting variables 573 0.90 0.69 0.98 1 17 216 265 74
Last updated 13 May 2009 (RF)

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