Consistency of the factorial validity of the WISC-R for upper and lower SES groups

The WISC-R was factor analyzed for both upper and lower SES classifications from the standardization sample. Both two- and three-factor solutions were extracted, and these solutions generally parallel other previously reported two- and three-factor WISC-R solutions. The stability of these factors was then examined by calculating coefficients of congruence and salient variable similarity indices between matched factor pairs from the two SES groups. The three-factor solution was the most appropriate for both groups, though the two-factor solution was equally plausible. The WISC-R factor structure appears to be invariant with regard to SES.