title: Enforcement uniquely predicts reductions in alcohol-impaired crash fatalities.
abstract: OBJECTIVE
  Alcohol-impaired driving contributes to more than 10 000 fatalities in the United States each year. This research estimated the unique effect of enforcement intensity on reductions in alcohol-impaired fatal crashes.
  
  
  METHODS
  We collected data from 30 states (including the District of Columbia) that experienced the greatest changes in alcohol-impaired fatal crashes from 1996 to 2006. Mixed-model regression was used to examine the extent to which year-over-year changes in the intensity of impaired driving enforcement predicted year-over-year reductions of drivers killed in alcohol-involved fatal crashes.
  
  
  METHODS
  Data from 30 states were obtained online.
  
  
  METHODS
  Aggregate state-level data from a total of 279 state-year combinations were analyzed.
  
  
  METHODS
  Our dependent measure was the ratio of drivers involved in fatal crashes with blood alcohol concentrations (BACs) ≥ 0.08 g/dl over drivers involved in fatal crashes with BACs = 0.00 g/dl. Per capita driving under the influence (DUI) arrests and traffic enforcement funding were the primary predictors. Covariates were estimated vehicle miles traveled (VMT); the proportional distributions of gender and racial/ethnic; geographic distribution; the proportion of drivers aged 21-34 years; median family income; and education level.
  
  
  RESULTS
  Analysis revealed that DUI arrests per capita uniquely and significantly predicted reductions in the ratio of fatal crashes (β = -0.753, t(238)  = 2.1, P < 0.05) after controlling the covariates. Exploratory analysis suggests the increase in arrest rates was associated with stronger reductions in urban versus rural settings.
  
  
  CONCLUSIONS
  Drunk driving enforcement intensity uniquely contributes to reductions in alcohol-impaired crash fatalities after controlling for other factors.
authors.affiliation: Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China.
authors.forename: Julie
authors.initials: J
authors.lastname: Yao
authors.affiliation: Pacific Institute for Research and Evaluation, Calverton, MD, USA.
authors.forename: Mark B
authors.initials: MB
authors.lastname: Johnson
authors.affiliation: Pacific Institute for Research and Evaluation, Calverton, MD, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Tippetts
mesh_terms: D000063:Accidents, Traffic / Q000401:mortality* / Q000517:prevention & control; D000328:Adult; D000368:Aged; D000066448:Driving Under the Influence / Q000331:legislation & jurisprudence* / Q000517:prevention & control; D005260:Female; D006801:Humans; D007182:Income; D035846:Law Enforcement; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D014481:United States; D055815:Young Adult
keywords: DUI reduction; Drinking and driving; deterrence; drunk driving; enforcement; fatal crashes