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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, Grade 4 Science Combined National and State Main Assessment: 2005

NAEP Technical DocumentationProportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, grade 4 science combined national and state main assessment: 2005
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.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005 Science Assessment.
All contrasts 1,434 0.90 0.58 1.00 16 128 460 396 434
Student questionnaire 134 0.90 0.58 0.99 2 9 51 41 31
Major reporting variables 96 0.93 0.73 1.00 0 2 23 23 48
Interactions between reporting variables 516 0.90 0.60 0.99 13 31 154 159 159
Teacher questionnaire 554 0.89 0.71 0.99 0 77 189 124 164
School questionnaire 134 0.90 0.66 0.99 1 9 43 49 32
Last updated 13 May 2009 (RF)

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