Reliability and validity of composite scores from the timed subtests of the D-KEFS battery.

Many neuropsychological tests of executive functioning (EF) have test-retest reliabilities below what is considered acceptable. Combining several tests into a composite can improve reliability, although due to concerns about the multifaceted nature of the EF construct, this practice is rarely applied. The present study (a) examined internal consistencies and test-retest reliabilities of two composites of four EF tests ( EF-Speed from timed scores and EF-Accuracy from error scores), and (b) preliminarily examined the criterion validity of the composites as a first step toward construct validation. Participants were 576 adults aged 18-93. Participants completed timed subtests of the Delis-Kaplan Executive Function System (D-KEFS) at baseline. A subset of participants was retested twice (at 30 min and 1 year), or once (at 6 weeks). An additional subsample completed Timed Instrumental Activities of Daily Living (TIADLs), which was used to preliminarily examine the composites' criterion validity. Internal consistency and test-retest reliabilities ranged from good to excellent for the EF-Speed composite (.809-.901) but were poor to acceptable for the EF-Accuracy composite (.510-.736). Both composites surpassed reliabilities of individual test or condition scores; one third of the examined individual speed-based scores and none of the individual error-based scores met the acceptable reliability threshold (i.e., < .7). The EF-Speed composite accounted for more variance in TIADL speed, and the EF-Accuracy in TIADL accuracy, than did any of the individual test scores, providing preliminary evidence of clinical utility and criterion validity. (PsycInfo Database Record (c) 2022 APA, all rights reserved).