Several states lowered the legal drinking age to 18 between 1971 and 1973. The objectives of this research were: (1) to determine if alcohol-related highway crashes increased among legally-affected populations of drivers in three study states, and (2) to determine, if changes were found in the frequencies of alcohol-related crashes, whether a causal relationship exists between the crash experience increases and the legal changes. Seven states were studied in a multiple time-series quasi-experimental design. A surrogate measure dependent variable was developed consisting of late right, single-vehicle crash involvements with male drivers. A surrogate was determined to be necessary in that officially reported alcohol involvement statistics were found to be inconsistently measured over time and incomparable between states. The developed three-factor surrogate was found to be consistently 53-66% alcohol-related. Through controlled time-series analyses including the utilization of the Box-Tiao (1965) auto- regressive time-series "t" statistic, it was found that statistically and socially significant increases in alcohol- related crashes resulted in Michigan and in Maine following the effective dates of the 18-year-old legal drinking ages. No concommitant changes were found in Vermont, another transitional state, or in any of the four control states. Analyses of age-specific alcohol-related crash frequency distributions provided support and explanation for the results of the time-series analyses, and provided a basis for prediction regarding the expected effect of the lower legal drinking age on youth crash involvement.

  • Corporate Authors:

    Highway Safety Research Institute

    Huron Parkway and Baxter Road
    Ann Arbor, MI  United States  48109
  • Authors:
    • Douglass, R L
  • Publication Date: 1974-10

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 1-15

Subject/Index Terms

Filing Info

  • Accession Number: 00081453
  • Record Type: Publication
  • Source Agency: Highway Safety Research Institute
  • Files: TRIS
  • Created Date: Mar 26 1975 12:00AM