The Practical Validity of g
Practical validity is indicated by a significant and predictively useful correlation of a measurement with some educational, economic, or social criterion that is deemed important by many people. The g factor (and highly g-loaded test scores, such as the IQ) shows a more far-reaching and universal practical validity than any other coherent psychological construct yet discovered. It predicts performance to some degree in every kind of behavior that calls for learning, decision, and judgment. Its validity is an increasing monotonic function of the level of cognitive complexity in the predicted criterion. Even at moderate levels of complexity of the criterion to be predicted, g is the sine qua non of test validity. The removal of g (by statistical regression) from any psychometric test or battery, leaving only group factors and specificity, absolutely destroys their practical validity when they are used in a population that ranges widely in general ability.
The validity of g is most conspicuous in scholastic performance, not because g-loaded tests measure specifically what is taught in school, but because g is intrinsic to learning novel material, grasping concepts, distinctions, and meanings. The pupil's most crucial tool for scholastic learning beyond the primary grades--reading comprehension--is probably the most highly g-loaded attainment in the course of elementary education.
In the world of work, g is the main cognitive correlate and best single predictor of success in job training and job performance. Its validity is not nullified or replaced by formal education (independent of g), nor is it decreased by increasing experience on the job.
Although g has ubiquitous validity as a predictor of job performance, tests that tap other ability factors in addition to g may improve