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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 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, Age 9 Mathematics Long-Term Trend Assessment: 2012
| Type of contrast | Number of contrasts | Mean | Minimum | Maximum | Number of contrasts by proportion1 of variance explained | ||||
|---|---|---|---|---|---|---|---|---|---|
| 0.00 - 0.70 | 0.70 - 0.80 | 0.80 - 0.90 | 0.90 - 0.95 | 0.95 - 1.00 | |||||
| 1 (Total Variance – Residual Variance)/Total Variance, where Total Variance consists of both sampling and measurement error variance. NOTE: SD/ELL = Students with disabilities/English language learners. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2012 Mathematics Long-Term Trend Assessment. |
|||||||||
| All contrasts | 423 | 0.90 | 0.68 | 0.99 | 1 | 34 | 140 | 146 | 102 |
| Student questionnaire | 63 | 0.90 | 0.71 | 0.99 | 0 | 13 | 11 | 14 | 25 |
| Major reporting variables | 77 | 0.92 | 0.77 | 0.99 | 0 | 3 | 18 | 20 | 36 |
| Interactions between reporting variables | 244 | 0.89 | 0.68 | 0.97 | 1 | 14 | 96 | 104 | 29 |
| SD/ELL questionnaire | 39 | 0.90 | 0.74 | 0.99 | 0 | 4 | 15 | 8 | 12 |
Last updated 20 September 2013 (JL)
