A comparison of the WAIS and WAIS-R in matched UK samples.

A matched samples design was employed to compare WAIS and WAIS-R IQ in UK subjects. The WAIS yielded significantly higher mean Full Scale, Verbal and Performance IQs. The mean differences were 7.5, 6.4 and 7.9 IQ points respectively. The WAIS and WAIS-R samples were broadly representative of the UK adult population in terms of age, sex and social class distribution, and therefore provide tentative estimates of population mean scores for both Wechsler scales. Mean WAIS IQ was 108.6, suggesting that the WAIS yields inflated IQ scores in the contemporary UK population. Encouragingly, mean WAIS-R Full Scale IQ was 101.1, suggesting that it neither markedly underestimates nor overestimates IQ in the UK.