Use of demographic variables to predict full scale IQ: a replication and extension.

The evaluation of current level of neuropsychological functioning is handicapped by the lack of validated actuarial methods for estimating premorbid intellectual functioning. The present study cross-validated and attempted to improve the one existing method of using demographic variables in a systematic way to predict WAIS Full Scale IQ (Wilson et al., 1978). A sample of 491 neurologically normal subjects was used. The results generally supported the IQ prediction equation, but did reveal systematic differences in accuracy of prediction and direction of prediction error for IQs in the high and low ranges. Also, a simpler IQ prediction formula that uses only years of education was developed and compared with the 5-variable Wilson et al. formula.