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 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 Main Assessment: 2006

NAEP Technical DocumentationProportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, grade 8 civics national main assessment: 2006

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. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006 Civics Assessment.
All contrasts	1096	0.90	0.62	0.99	8	42	448	359	239
Student questionnaire	154	0.88	0.62	0.99	3	14	63	51	23
Major reporting variables	59	0.93	0.83	0.99	0	0	24	7	28
Interactions between reporting variables	528	0.91	0.65	0.99	5	17	140	214	152
Teacher questionnaire	222	0.89	0.76	0.98	0	11	112	72	27
School questionnaire	133	0.88	0.81	0.98	0	0	109	15	9

Printer-friendly Version