Development of a Behind-the-Wheel Driving Assessment of Older Adults
Principal Investigator: Michael D. Justiss
This study seeks to standardize scoring of behind-the-wheel driver assessment, focusing on older drivers. The behind-the-wheel (BTW) driving assessment has been identified as the most appropriate method to determine driving competence. Despite attempts to quantify driving performance, the accepted global criterion outcome (pass/fail) is determined by evaluator judgment rather than a quantifiable driving score. Information gathered from expert consensus was utilized to develop the on-road driving assessment. Recommendations were given for a fixed-route, a gradual progression of driving difficulty, and total driving time of approximately one hour. Scoring is based on behavioral errors during driving maneuvers. The difference in scoring compared to previous research is that maneuvers are scaled for severity of error and grouped into three levels of driving complexity. A total performance score is then calculated. This score is compared to the Global Outcome Rating determined by the evaluator. The outcome rating is based on evaluator judgment (criterion standard) and has four levels: Safe (3), Safe with restrictions or recommendations (2), Unsafe Remediable (1), Unsafe not remediable (0). This study will analyze the criterion validity, inter-rater reliability, internal consistency, and test-retest reliability of this measurement tool. After test-retest reliability has been established, the stability of this scoring mechanism will be analyzed across to different road courses of similar design to see if it can account for geographic variability. An analysis of performance items will be conducted using modern test theory to verify the hierarchy of item difficulty and its ability to discriminate levels of driving performance.