Criterion Validity of the WAIS-IV Cognitive Proficiency Index (CPI)

Objective: The current study sought to validate the Cognitive Proficiency Index (CPI) against similar, well-established measures of attention and processing speed. Additionally, the sensitivity of the CPI and Attention Index of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and their ability to differentiate among clinical groups were compared. Method: The first objective was accomplished by calculating correlation coefficients between the CPI and similar attention and processing speed measures. The second objective was accomplished using a clinical group of 25 individuals with Mini-Mental State Exam (MMSE) scores of less than or equal to 23 matched to a non-clinical group of 43 participants with MMSE scores of 30, all derived from the original sample. Results: The CPI correlated in expected ways with other measures of attention and processing speed (magnitude of r=.19-.77). ANCOVA, receiver operating characteristic, and discriminant function analyses suggested that the CPI is superior to the RBANS Attention Index in differentiating between clinical and non-clinical groups. Conclusions: These findings provide support for convergent validity and criterion-related concurrent validity for the CPI.