Redundancy in the Stanford Achievement Test

Abstract

The Stanford Achievement Test, Advanced, provides nine subtests which are often used by schools as normed measures of school achievement. As part of a larger study, the relation between each of these subtests and measures of special aptitudes and temperament traits was studied with a sample of 226 eighth graders. Principal factors were sought. The first eigenvalue was 6.64; the second was 0.64; the remaining eigenvalues were less than one. Convergence was obtained in eight iterations. A plot of the first factor against the second showed that all points were included in an angle of 45 degrees with several of the verbal measures clustering on one factor and all the mathematics measures clustering on the other. Results suggested the need for new discriminant validity studies of the test.