A comparison of WISC-R and WAIS-R IQS in a mentally retarded residential population

Although typically regarded as equivalent instruments, the WISC-R and the WAIS-R yield significantly different Verbal, Performance, and Full Scale IQs for an intellectually subaverage group, with the WAIS-R consistently providing higher scores. Implications of this “built-in” increment for issues of eligibility for educational placements and societal benefits are serious, and careful interpretation of IQs in the context of other relevant data is necessary.