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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, Grade 8 Civics National Assessment, by Type of Contrast: 2018
| Type of contrast | Number of contrasts | Mean | Minimum | Maximum | Number of contrasts by proportion of variance explained1 | ||||
|---|---|---|---|---|---|---|---|---|---|
| .00 - .70 | .70 - .80 | .80 - .90 | .90 - .95 | .95 - 1.00 | |||||
All contrasts | 1657 | .80 | .54 | .98 | 234 | 611 | 516 | 225 | 71 |
| Student questionnaire | 493 | .75 | .54 | .97 | 164 | 201 | 47 | 76 | 5 |
| Major reporting variables | 317 | .83 | .58 | .98 | 11 | 73 | 178 | 30 | 25 |
| Interactions between reporting variables | 241 | .81 | .60 | .97 | 45 | 69 | 50 | 62 | 15 |
| Teacher questionnaire | 422 | .81 | .71 | .98 | 0 | 213 | 159 | 37 | 13 |
| School questionnaire | 154 | .84 | .75 | .98 | 0 | 44 | 78 | 19 | 13 |
| SD/EL questionnaire | 30 | .72 | .60 | .91 | 14 | 11 | 4 | 1 | 0 |
|
1 (Total Variance – Residual Variance) / Total Variance, where Total Variance includes sampling, measurement, and other sources of error. NOTE: DBA = Digitally based assessment. SD/EL = Students with disabilities/English learners. Because not all initial contrasts are included in the final population-structure model for a given assessment, the civics DBA and PBA may not have the same number of contrasts. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2018 Civics Assessment. | |||||||||
| Type of contrast | Number of contrasts | Mean | Minimum | Maximum | Number of contrasts by proportion of variance explained1 | ||||
|---|---|---|---|---|---|---|---|---|---|
| .00 - .70 | .70 - .80 | .80 - .90 | .90 - .95 | .95 - 1.00 | |||||
All contrasts | 1521 | .80 | .51 | .98 | 319 | 324 | 644 | 169 | 65 |
| Student questionnaire | 507 | .74 | .51 | .97 | 222 | 147 | 93 | 40 | 5 |
| Major reporting variables | 228 | .85 | .54 | .98 | 17 | 6 | 166 | 21 | 18 |
| Interactions between reporting variables | 238 | .80 | .55 | .98 | 63 | 47 | 52 | 60 | 16 |
| Teacher questionnaire | 385 | .83 | .70 | .98 | 1 | 116 | 226 | 27 | 15 |
| School questionnaire | 133 | .87 | .80 | .98 | 0 | 1 | 101 | 20 | 11 |
| SD/EL questionnaire | 30 | .71 | .57 | .92 | 16 | 7 | 6 | 1 | 0 |
|
1 (Total Variance – Residual Variance) / Total Variance, where Total Variance includes sampling, measurement, and other sources of error. NOTE: PBA = Paper-based assessment. SD/EL = Students with disabilities/English learners. Because not all initial contrasts are included in the final population-structure model for a given assessment, the civics DBA and PBA may not have the same number of contrasts. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2018 Civics Assessment. | |||||||||
Last updated 27 January 2023 (ML)