The factor structure of the Wechsler Adult Intelligence Scale-Revised: one or two but not three factors.

One-, 2-. and 3-factor solutions for the WAIS-R normative samples were examined using principal components analysis with varimax rotations. Factors were examined across age groups by computing congruence coefficients and root mean square differences to determine the equivalence and consistency of factors across age groups. There is strong evidence for the general (g) and 2-factor (verbal and perceptual organization) solutions but noticeably less support for memory/freedom from distractibility in the three-factor solution. Verbal and perceptual organization factors were also attenuated in the three-factor solution. One and 2-factor solutions were essentially equally justifiable but because the 1-factor solution was weighted most heavily with verbal measures, the 2-factor solution may be advantageous because this solution does distinguish between verbal and performance measures.