Comparison of two IQ conversion tables for the Vocabulary-Block Design short form

This study compared Brooker and Cyr (1986) and Silverstein (1982) WAIS-R IQ conversion tables for the Vocabulary-Block Design combination. Subjects were 150 veterans unselected with respect to diagnosis. Means for Full Scale IQ, Brooker and Cyr IQ, and Silverstein IQ were 94.17 (SD = 15.05), 96.68 (SD = 15.35), and 96.87 (SD = 15.30), respectively. Correlations between Full Scale IQ and both IQ estimates were highly significant: Brooker and Cyr r(148) = .91, p less than .001; Silverstein r(148) = .92, p less than .001. Both short-form IQs overestimated Full Scale IQ; average difference of 1.51 points for Brooker and Cyr and 1.67 for Silverstein were found. Agreement between both short form IQ estimates and Full Scale in terms of Wechsler's seven category intelligence classification was 62%. Both conversion tables yield comparable Full Scale IQ estimates.