tent with the PPIK theory, and with the earlier results, Science/Math/Tech-
nology trait complex was supportive of knowledge in the Physical Sciences/
Technology domain, and the Verbal/Intellectual trait complex was suppor-
tive of knowledge in all of the measured domains. A structural equation
model of the trait complexes and domain knowledge is shown in Fig. 5.5.
Even though this sample was undoubtedly restricted in range at the higher
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FIG. 5.4. LISREL structural equation model for ability factors and knowl-
edge factors. Lines indicate significant path coefficients. Gf = fluid intelligence;
Gc = Crystallized intelligence. Reprinted from Ackerman et al. (2001). Copy-
right American Psychological Association. Reprinted by permission.