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NAEP Analysis and ScalingEstimation of Population and Student Group DistributionsExamining the Population-Structure Models Used in NAEPProportion of Variance Accounted for by Principal Components Used in NAEP Population-Structure Models → Proportion of Variance of the Group-Defining Contrasts Accounted for by the Principal Components Used in the Population-Structure Model, Grade 12 Mathematics National Assessment, by Type of Contrast: 2019

​​NAEP Technical DocumentationProportion of Variance of the Group-Defining Contrasts Accounted for by the Principal Components Used in the Population-Structure Model, Grade 12 Mathematics National Assessment, by Type of Contrast: 2019

Proportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, grade 12 mathematics DBA national assessment, by type of contrast: 2019
Type of contrast Number of contrasts Mean Minimum Maximum Number of contrasts by proportion of variance explained
.00 - .70 .70 - .80 .80 - .90 .90 - .95 .95 - 1.00
(Total Variance – Residual Variance) / Total Variance, where Total Variance includes variance accounted and unaccounted for by the variables in the population-structure model.
DBA = Digitally based assessment. SD/EL = Students with disabilities/English learners.
U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2019 Mathematics Assessment.
All contrasts 1414 .90 .72 .99 0 40 599 577 198
Student questionnaire 530 .91 .75 .98 0 13 166 252 99
Major reporting variables 78 .92 .82 .99 0 0 31 23 24
Interactions between reporting variables 323 .89 .72 .98 0 24 125 139 35
School questionnaire 452 .89 .78 .97 0 3 263 153 33
SD/EL questionnaire 31 .89 .80 .96 0 0 14 10 7


Proportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, grade 12 mathematics PBA national assessment, by type of contrast: 2019
Type of contrastNumber of contrastsMeanMinimumMaximumNumber of contrasts by proportion of variance explained
.00 - .70.70 - .80.80 - .90.90 - .95.95 - 1.00
(Total Variance – Residual Variance) / Total Variance, where Total Variance includes variance accounted and unaccounted for by the variables in the population-structure model.
PBA = Paper-based assessment. SD/EL = Students with disabilities/English learners.
U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2019 Mathematics Assessment.
All contrasts1444.90.71.99045591619189
Student questionnaire553.91.72.9802416527193
Major reporting variables83.92.78.9901292825
Interactions between reporting variables329.90.71.9801712115338
School questionnaire449.89.79.980126415925
SD/EL questionnaire30.89.77.97021288


Last updated 05 October 2023 (SK)