Table 2.

Advantages and Disadvantages of Different Sources of Evidence of Driving Competency

Source	Advantages	Disadvantages
Driving simulation	Safe, without injury risks of road or test track Best means to replicate exactly experimental road conditions under which driver decisions are made Can be used to quantify performance profiles in cognitively impaired drivers (eg, advanced age, Alzheimer disease, Parkinson disease, stroke, traumatic brain injury, multiple sclerosis, obstructive sleep apnea, alcohol/drug use)	Drivers may behave differently in a simulator, where no injury can occur Testing validity may require laborious detailed comparisons with state records of crashes and moving violations and with real-life performance in an instrumented vehicle or in a state road test Simulator adaptation syndrome
State road test2	Considered gold standard of driver fitness Assesses driving performance under direct supervision of trained expert Performance graded along several dimensions to calculate cutoff score used to designate drivers as safe or unsafe	Developed to ensure that novice drivers know and apply rules of the road, not to test experienced drivers who may be impaired Few data show that road tests correlate with crash involvement Risk of the road to the driver and examiner Test conditions vary depending on weather, daylight, traffic, and route Driving experts have different biases and grading criteria
Instrumented vehicles	Permit quantitative assessment of driver performance under actual road conditions Assessment can incorporate standard maneuvers deemed essential to driving such as turns, observance of traffic signs and signals, maintenance of vehicle control, and response to standard cognitive challenges (eg, route finding; sign identification; multitasking, as in conversation or using in-vehicle telematics devices such as cell phones and navigation devices) while driving Measurements are not subject to human bias that affects interrater reliability on a standard road test	Risk of the road environment
Event recorders	Deployed in driver's own vehicle, these black box systems allow detailed assessment of driver safety in naturalistic settings over extended times without an examiner present May disclose specific situations or settings in which a driver is prone to making safety errors	Confidentiality of electronic and video data Taxonomies of understanding errors are needed
State crash records	Often provide main basis for judging fitness of drivers who have not had road test Are more accurate and impartial than reports of drivers, relatives, and friends Provide details on time of day, road and weather conditions, and crash type, which drivers may forget	Crashes are uncommon, and unsafe drivers may not have had a crash Some crashes are inevitable, caused by factors extrinsic to the driver Driver reporting of crashes may be unreliable Individuals with faulty memory underreport crashes Injured parties may not remember what happened Single car crashes often have no reliable witnesses No direct observations of actions leading up to a crash Specific details on mechanisms of a crash are generally missing