Data from a previous adoption study using the Wechsler Intelligence Scale for Children-Revised show that the genetic effect is reflected by psychometric "g" (general intelligence) to a greater degree than is the environmental effect. This finding is consistent with the hypothesis that "g" largely reflects the genetic component…

The specificity doctrine, holds that psychometric tests measure nothing other than the specific bits of knowledge and learned skills reflected in the item content of the tests. This prevailing doctrine has influenced the interpretation of test scores and the conceptualization of test validity, as well as the practical use of tests in educational…

The stability of psychometric "g," the general factor of intelligence, is investigated in simulated correlation matrices and in typical empirical data from a large battery of mental tests. "G" is robust and almost invariant across methods of analysis. A reasonable strategy for estimating "g" is suggested. (SLD)

The hypothetical idea of a perfectly pure psychometric "g" is empirically unattainable. Because the unity of "g" cannot be proved or disproved by factor analysis, the unitary "g" hypothesis represents a parsimonious assumption. J. B. Carroll's (1991) analysis demonstrates the relationship between psychometric and…