The Wechsler Adult Intelligence Scale-IV Cognitive Proficiency Index: alternate form reliability of the nine possible subtest tetrads

The Wechsler Adult Intelligence Scale (WAIS-IV) added a new interpretative level by assigning the ten standard subtests into one of two constructs, the General Ability Index or the Cognitive Proficiency Index (CPI). The CPI, inferred to be a non-intellective measure of information processing efficiency, is composed of the two Working Memory Index and the two Processing Speed Index subtests (DS, AR, CD, SS). However, each index has one supplemental subtest that can be used in place of a standard one, thereby creating nine possible CPI tetrads, except for senior adults 70-90. Measuring the equivalence reliability of the nine alternate CPI tetrads was the aim of this study. Using the WAIS-IV standardization data, it was shown that all nine CPI tetrads have exceptionally high subtest equivalence reliability (.90+). For neuropsychological research purposes, all nine CPI constructions can be considered interchangeable, alternate-form measures of composite information processing efficiency. However, more research is needed to establish their accuracy for individual assessment, as well as to measure the other important reliability and predictive construct validity characteristics of the nine CPI tetrads.