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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 17 Reading 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 Reading Long-Term Trend Assessment. |
|||||||||
| All contrasts | 485 | 0.90 | 0.64 | 0.99 | 5 | 34 | 149 | 194 | 103 |
| Student questionnaire | 76 | 0.90 | 0.64 | 0.99 | 1 | 6 | 18 | 27 | 24 |
| Major reporting variables | 81 | 0.92 | 0.75 | 0.99 | 0 | 4 | 24 | 20 | 33 |
| Interactions between reporting variables | 296 | 0.90 | 0.67 | 0.98 | 4 | 19 | 97 | 138 | 38 |
| SD/ELL questionnaire | 32 | 0.89 | 0.77 | 0.98 | 0 | 5 | 10 | 9 | 8 |
Last updated 20 September 2013 (JL)
