The WAIS-R(UK): basic psychometric properties in an adult UK sample

The WAIS-R is the most widely used measure of intellectual ability in the UK, despite never having been standardized in this country. The present study examined the psychometric properties of the WAIS-R in a sample of 200 subjects, which was representative of the adult UK population in terms of the distributions of age, sex and social class. The properties of the three IQ scales, i.e. the FSIQ, the VIQ and the PIQ, were found to be very similar to those reported for the US standardization sample: the scores were normally distributed, with means close to the desired value of 100; moreover, the reliabilities of the IQ scales were extremely high and closely matched the US reliabilities. There were also indications, however, that the scales have restricted standard deviations when used in the UK. The reliabilities of the 11 original subtests ranged from moderate to high and the majority were similar to the US reliabilities. However, in addition to evidence of restricted SDs, significant differences (sometimes as much as two-thirds of an SD) were found among the subtest means. These in-built subtest discrepancies could lead to erroneous conclusions about an individual's performance. A conversion table for UK test users is provided to overcome this problem.