Relative subtest scatter in the WAIS-IV standardization sample.

The frequencies of differences between highest and lowest subtest scores as a function of highest subtest score (relative scatter), are reported for the standardization sample of the Wechsler Adult Intelligence Scale-IV (WAIS-IV). Large differences between highest and lowest subtest scores were common. The degree of relative scatter was related to the height of the highest subtest score. For the 10 core WAIS-IV subtests, the correlation between the level of the highest subtest score and the amount of scatter was r = .62; for all 15 subtests the correlation was. 63. The level of the highest subtest score was more strongly related to scatter than was Full Scale IQ. Clinical implications for inferring cognitive impairment and estimating premorbid abilities are discussed. When considering the possibility of acquired cognitive impairment, we recommend caution in the interpretation of subtest score differences.