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Table of Contents | Search Technical Documentation | References
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 8 Writing Combined National and State Main Assessment: 2002
| Type of contrast | Number of contrasts | Mean | Minimum | Maximum | Number of contrasts by proportion of variance explained | ||||
|---|---|---|---|---|---|---|---|---|---|
| 0.00 - 0.70 | 0.70 - 0.80 | 0.80 - 0.90 | 0.90 - 0.95 | 0.95 - 1.00 | |||||
| NOTE: A value of 1.00 in the table does not imply that all of a single contrast's variance is accounted for by the set of principal components. Rather, the proportion of variance accounted for is high and is closer to 1.00 than any other number when expressed with two decimals of precision. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2002 Writing Assessment. |
|||||||||
| All contrasts | 1377 | 0.90 | 0.64 | 1.00 | 5 | 104 | 489 | 414 | 365 |
| Student questionnaire | 213 | 0.89 | 0.64 | 0.99 | 3 | 25 | 67 | 71 | 47 |
| Major reporting variables | 100 | 0.92 | 0.76 | 1.00 | 0 | 1 | 30 | 37 | 32 |
| Interactions between reporting variables | 343 | 0.90 | 0.70 | 0.99 | 1 | 30 | 123 | 107 | 82 |
| Teacher questionnaire | 366 | 0.90 | 0.70 | 0.98 | 1 | 35 | 115 | 102 | 113 |
| School questionnaire | 355 | 0.90 | 0.73 | 1.00 | 0 | 13 | 154 | 97 | 91 |
Last updated 25 March 2009 (RF)
