The AFQT has been used in non-military settings as a proxy measure of intelligence, for example, in Herrnstein & Murray's book The Bell Curve. Because of the test's significance both inside and outside military settings, it is important to examine what the test measures, i.e. to evaluate the construct validity of the AFQT. Kaufman's 2010 review stated that David Marks (2010) scanned the literature for datasets containing test estimates for populations or groups taking both the AFQT and tests of literacy. One study on nine groups of soldiers differing in job and reading ability found a correlation of .96 between the AFQT and reading achievement (Sticht, Caylor, Kern, & Fox, 1972). Another study showed significant improvements among Black and Hispanic populations in their AFQT scores between 1980 and 1992 while Whites only showed a slight decrement (Kilburn, Hanser, & Klerman, 1998). Another study obtained reading scores for 17-year olds for those same ethnic groups and dates (Campbell et al., 2000) and found a correlation of .997 between reading scores and AFQT scores. This nearly perfect correlation was based on six pairs of data points from six independent population samples evaluated by two separate groups of investigators. According to Marks, "On the basis of the studies summarized here, there can be little doubt that the Armed Forces Qualifications Test is a measure of literacy." However, it is important to note that AFQT has been shown to correlate more highly with classic IQ tests than they do with one another, and that the "crystallized" intelligence measured by AFQT is measured very similarly by Wechsler, in particular.
Mathematics Knowledge tests the ability to solve problems by applying knowledge of mathematical concepts and applications. The problems focus on concepts and algorithms, and involve number theory, numeration, algebraic operations and equations, geometry, measurement and probability. Mathematics Knowledge is one factor that characterizes mathematics comprehension; it also assesses logical thinking.