Disparities in mentally retarded persons' IQs derived from different intelligence tests.

For mildly and moderately mentally retarded individuals, the Wechsler Adult Intelligence Scale--Revised measures at about the same level as the Wechsler Adult Intelligence Scale, and, consequently, it also produces much higher IQs than do the Wechsler children's scales or the Stanford-Binet Intelligence Scale, Form L-M, despite high intertest correlations. This unsatisfactory state of affairs is due primarily to inadequate standardization sampling, particularly in the lower range of intelligence. Rather than abandon the IQ, corrective action should be taken.