NAEP Technical Documentation Proportion of Variance of the Group-Defining Contrasts Accounted for by the Principal Components Used in the Population-Structure Model, Grade 4 Science Combined National and State Assessment, by Type of Contrast: 2015

Proportion of variance of the group-defining contrasts accounted for by the principal components used in the population-structure model, grade 4 science combined national and state assessment, by type of contrast: 2015

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	2257	.90	.66	1.00	5	57	1074	664	457
Student questionnaire	183	.91	.70	.98	0	12	49	91	31
Major reporting variables	127	.92	.77	1.00	0	1	39	41	46
Interactions between reporting variables	282	.89	.66	.97	5	14	106	124	33
Teacher questionnaire	912	.90	.75	.99	0	23	437	219	233
School questionnaire	716	.89	.78	.99	0	6	430	182	98
SD/EL questionnaire	37	.91	.79	.99	0	1	13	7	16
1 (Total Variance – Residual Variance) / Total Variance, where Total Variance consists of sampling, measurement, and other sources of error. NOTE: SD/EL = Students with disabilities/English learners. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

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