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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 the 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 13 Reading Long-Term Trend Assessment: 2008
| 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), 2008 Reading Long-Term Trend Assessment. |
|||||||||
| All contrasts | 683 | 0.90 | 0.63 | 0.99 | 15 | 55 | 199 | 222 | 192 |
| Student questionnaire | 85 | 0.89 | 0.63 | 0.99 | 2 | 14 | 19 | 27 | 23 |
| Major reporting variables | 62 | 0.89 | 0.67 | 0.99 | 1 | 7 | 26 | 7 | 21 |
| Interactions between reporting variables | 497 | 0.90 | 0.63 | 0.98 | 12 | 30 | 139 | 176 | 140 |
| SD/ELL questionnaire | 39 | 0.89 | 0.78 | 0.98 | 0 | 4 | 15 | 12 | 8 |
Last updated 14 December 2011 (GF)
