Within-Person Score Distribution Measures as Performance Validity Indicators in Service Members and Veterans with and without History of Mild Traumatic Brain Injury.

OBJECTIVE

This study examined within-person score distribution measures (WPSD) as a performance validity indicator using the overall test battery mean (OTBM), within-battery standard deviation (SD-B), coefficient of variation (CV), number of abnormal scores (ABN), and several other measures. The primary aim was comparison of classification accuracy of various WPSD measures.

METHOD: The study involved secondary analysis of de-identified data originally collected in the Chronic Effects of Neurotrauma Consortium Study 1. Participants (N = 1431) were categorized into valid and questionable performance validity groups using independent performance validity tests (PVTs). Seven WPSD measures were calculated from norm-referenced T scores on 24 cognitive tests: OTBM, CV, SD-B, kurtosis, skew, range, and ABN (scores ≤35 T). Area under the receiver operating characteristic curve (AUC) values were compared across WPSD measures.

RESULTS

Significant group differences were observed in OTBM, CV, and ABN. AUC comparison showed excellent classification accuracy for OTBM (AUC = 0.83) and ABN (AUC = 0.84), and acceptable accuracy for CV (AUC = 0.74). Minimum specificity (≥90%) was shown with cutoffs on OTBM (≤42 T; sensitivity = 56%), CV (≥0.265; sensitivity = 30%), and ABN (≥6; sensitivity = 55%). Slight adjustments were required to maintain specificity in racially and ethnically diverse sample subsets.

CONCLUSIONS

OTBM and ABN demonstrated strong potential for use as embedded PVTs with excellent classification accuracy. CV displayed lower classification accuracy with group differences primarily due to changes in mean performance rather than increased dispersion. Further development and cross-validation of WPSD-based PVTs is warranted in civilian samples.