title: Variability in crash and near-crash risk among novice teenage drivers: a naturalistic study.
abstract: OBJECTIVE
  Using video monitoring technologies, we investigated teenage driving risk variation during the first 18 months of independent driving.
  
  
  METHODS
  Driving data were collected on 42 teenagers whose vehicles were instrumented with sophisticated video and data recording devices. Surveys on demographic and personality characteristics were administered at baseline. Drivers were classified into 3 risk groups using a K-mean clustering method based on crash and near-crash (CNC) rate. The change in CNC rates over time was evaluated by mixed-effect Poisson models.
  
  
  RESULTS
  Compared with the first 3 months after licensure (first quarter), the CNC rate for participants during the third, fourth, and fifth quarters decreased significantly to 59%, 62%, and 48%, respectively. Three distinct risk groups were identified with CNC rates of 21.8 (high-risk), 8.3 (moderate-risk), and 2.1 (low-risk) per 10 000 km traveled. High- and low-risk drivers showed no significant change in CNC rates throughout the 18-month study period. CNC rates for moderate-risk drivers decreased substantially from 8.8 per 10 000 km in the first quarter to 0.8 and 3.2 in the fourth and fifth quarters, respectively. The 3 groups were not distinguishable with respect to personality characteristics.
  
  
  CONCLUSIONS
  Teenage CNC rates varied substantially, with distinct high-, moderate-, and low-risk groups. Risk declined over time only in the moderate-risk group. The high-risk drivers appeared to be insensitive to experience, with CNC rates consistently high throughout the 18-month study period, and the moderate-risk group appeared to learn from experience.
authors.affiliation: Department of Statistics, Virginia Tech, Blacksburg, VA; Virginia Tech Transportation Institute, Blacksburg, VA. Electronic address: feng.guo@vt.edu.
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Simons-Morton
authors.forename: Sheila E
authors.initials: SE
authors.lastname: Klauer
authors.forename: Marie Claude
authors.initials: MC
authors.lastname: Ouimet
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Dingus
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Lee
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D001334:Automobile Driving; D005260:Female; D006801:Humans; D008297:Male; D018570:Risk Assessment; D013997:Time Factors
keywords: 10K kmt; 10 000 km traveled; CNC; Crash and near-crash; NEO-FFI; NTDS; Naturalistic Teenage Driving Study; Neuroticism-Extroversion-Openness-Five Factor Inventory