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Mandatory Seatbelt Laws and Traffic Fatalities: A Reassessment


  • Anderson, D. Mark

    (Montana State University)

  • Liang, Yang

    (San Diego State University)

  • Sabia, Joseph J.

    (San Diego State University)


Using data from the Fatality Analysis Reporting System for the period 1983-1997, Cohen and Einav (Review of Economics and Statistics 2003; 85(4): 828–843) found that mandatory seatbelt laws were associated with a 4 to 6 percent reduction in traffic fatalities among motor vehicle occupants. After successfully replicating their two-way fixed effects estimates, we (1) add 22 years of data (1998-2019) to capture additional seatbelt policy variation and observe a longer post-treatment period, (2) employ the interaction-weighted estimator proposed by Sun and Abraham (2021) to address potential bias due to heterogeneous and dynamic treatment effects, and (3) estimate event-study models to investigate pre-treatment trends and explore lagged post-treatment effects. Consistent with Cohen and Einav (2003), our updated estimates show that primary seatbelt laws are associated with a 5 to 9 percent reduction in fatalities among motor vehicle occupants. Estimated effects of secondary seatbelt laws are smaller in magnitude and sensitive to model choice.

Suggested Citation

  • Anderson, D. Mark & Liang, Yang & Sabia, Joseph J., 2022. "Mandatory Seatbelt Laws and Traffic Fatalities: A Reassessment," IZA Discussion Papers 15843, Institute of Labor Economics (IZA).
  • Handle: RePEc:iza:izadps:dp15843

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    References listed on IDEAS

    1. David J. Houston & Lilliard E. Richardson, 2007. "Risk Compensation or Risk Reduction? Seatbelts, State Laws, and Traffic Fatalities," Social Science Quarterly, Southwestern Social Science Association, vol. 88(4), pages 913-936, December.
    2. Goodman-Bacon, Andrew, 2021. "Difference-in-differences with variation in treatment timing," Journal of Econometrics, Elsevier, vol. 225(2), pages 254-277.
    3. Richard A. Dunn & Nathan W. Tefft, 2020. "Replicating the Levitt and Porter estimates of drunk driving," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 35(6), pages 786-796, September.
    4. David J. Houston & Lilliard E. Richardson, Jr., 2006. "Reducing traffic fatalities in the American States by upgrading seat belt use laws to primary enforcement," Journal of Policy Analysis and Management, John Wiley & Sons, Ltd., vol. 25(3), pages 645-659.
    5. Steven D. Levitt & Jack Porter, 2001. "How Dangerous Are Drinking Drivers?," Journal of Political Economy, University of Chicago Press, vol. 109(6), pages 1198-1237, December.
    6. Marianne Bertrand & Esther Duflo & Sendhil Mullainathan, 2004. "How Much Should We Trust Differences-In-Differences Estimates?," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 119(1), pages 249-275.
    7. Steven D. Levitt, 2008. "Evidence that Seat Belts Are as Effective as Child Safety Seats in Preventing Death for Children Aged Two and Up," The Review of Economics and Statistics, MIT Press, vol. 90(1), pages 158-163, February.
    8. Sun, Liyang & Abraham, Sarah, 2021. "Estimating dynamic treatment effects in event studies with heterogeneous treatment effects," Journal of Econometrics, Elsevier, vol. 225(2), pages 175-199.
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    10. Carpenter, Christopher S. & Stehr, Mark, 2008. "The effects of mandatory seatbelt laws on seatbelt use, motor vehicle fatalities, and crash-related injuries among youths," Journal of Health Economics, Elsevier, vol. 27(3), pages 642-662, May.
    11. Lauren E. Jones & Nicolas R. Ziebarth, 2016. "Successful Scientific Replication and Extension of Levitt (2008): Child Seats are Still No Safer Than Seat Belts," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 31(5), pages 920-928, August.
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    14. Alma Cohen & Liran Einav, 2003. "The Effects of Mandatory Seat Belt Laws on Driving Behavior and Traffic Fatalities," The Review of Economics and Statistics, MIT Press, vol. 85(4), pages 828-843, November.
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    More about this item


    mandatory seatbelt laws; traffic fatalities; traffic safety;
    All these keywords.

    JEL classification:

    • C13 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Estimation: General
    • I12 - Health, Education, and Welfare - - Health - - - Health Behavior
    • K32 - Law and Economics - - Other Substantive Areas of Law - - - Energy, Environmental, Health, and Safety Law
    • K42 - Law and Economics - - Legal Procedure, the Legal System, and Illegal Behavior - - - Illegal Behavior and the Enforcement of Law

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