Controlling Gun Violence: Assessing the Impact of Australia’s Gun Buyback Program Using a Synthetic Control Group Experiment


Gun Buyback programs have been implemented in various forms in countries such as the UK, USA, Brazil, Australia, and Argentina. Whether or not these programs are an effective approach for reducing national violent crime and homicides, however, remains unclear. Much of the uncertainty is due to the different ways in which Gun Buyback programs have been implemented. The Australian Gun Buyback program is distinguished from Gun Buyback programs in other countries by its abrupt implementation, its narrow focus on a particular class of firearms, and its broad application across the entire population. We assess the impact of Australia’s 1996 Gun Buyback program on national homicide rates using a synthetic control group quasi-experimental design, comparing the results to suicide and motor vehicle fatality trends to test for plausible alternative hypotheses. Results suggest that the Gun Buyback program significantly reduced Australia’s homicide rate in the decade following the intervention (1997–2007).

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  1. 1.

    Throughout the 1967–2007 analysis timeframe, the 28 nations included in our analysis had no more than one sequential missing value. See the “Missing Data and Imputation” subsection of the supplementary materials for more detail.

  2. 2.

    Although Table 1 only reports the donor pool nations that contribute non-zero weights to Synthetic Australia, note that the homicide, suicide, and motor vehicle fatalities models all utilize the same 28 nation donor pool.

  3. 3.

    The difference emerges gradually across the 1997–2002 time period, in part, because of the 5-year moving average used to smooth year to year variation in the rate of a rare event.

  4. 4.

    When Synthetic Australia’s largest donor pool contributors (i.e., Norway, UK, etc) are iteratively excluded from the SCG minimization algorithm, the estimated reduction in homicides due to the 1996 gun buyback persists across each version of Synthetic Australia (i.e., our estimate is not dependent on the contribution of any particular donor pool nation). These results are available upon request.


  1. Abadie, A., & Gardeazabal, J. (2003). The economic costs of conflict: A case study of the Basque Country. American Economic Review, 113–132.

  2. Abadie, A., Diamond, A., & Hainmueller, J. (2010). Synthetic control methods for comparative case studies: Estimating the effect of California’s tobacco control program. Journal of the American Statistical Association, 105, 493–505.

    CAS  Article  Google Scholar 

  3. Abadie, A., Diamond, A., & Hainmueller, J. (2014). Comparative politics and the synthetic control method. American Journal of Political Science, 59, 495–510.

    Article  Google Scholar 

  4. ABC News Staff. (2019). “New Zealand PM Jacinda Ardern announces post-Christchurch ban on military-style semi-automatic weapons, assault rifles”. Australian Broadcasting Commision. March 20.

  5. Australasian Police Ministers’ Council Special Firearms Meeting, Resolutions, Canberra, 10 May, 1996. (retrieved 26 September 2018).

  6. Baker, J., & McPhedran, S. (2006). Gun laws and sudden death: Did the Australian firearms legislation of 1996 make a difference? British Journal of Criminology, 47, 455–469.

    Article  Google Scholar 

  7. Campbell, D. T. (1957). Factors relevant to the validity of experiments in social settings. Psychological Bulletin, 54, 297–312.

    CAS  Article  Google Scholar 

  8. Campbell, D. T. (1991). Methods for the experimenting society. American Journal of Evaluation, 12, 223–260.

    Article  Google Scholar 

  9. Campbell, D. T., & Stanley, J. C. (1966). Experimental and quasi-experimental designs for research. Boston: Houghton-Mifflin.

    Google Scholar 

  10. Card, D., & Krueger, A. B. (1994). Minimum wages and employment: A case study of the fast-food industry in New Jersey and Pennsylvania. American Economic Review, 84, 772–793.

    Google Scholar 

  11. Chapman, S., Alpers, P., Agho, K., & Jones, M. (2006). Australia’s 1996 gun law reforms: Faster falls in firearm deaths, firearm suicides, and a decade without mass shootings. Injury Prevention, 12, 365.

    CAS  Article  Google Scholar 

  12. Chew, K. S.-Y., & McCleary, R. (1995). The spring peak in suicides: A cross-national analysis. Social Science and Medicine, 40, 223–230.

    CAS  Article  Google Scholar 

  13. Durkheim, E. (1951[1897]). Suicide. New York: Free Press.

    Google Scholar 

  14. Hahn, R. A., Bilukha, O., Crosby, A., Fullilove, M. T., Liberman, A., Moscicki, E., & Briss, P. A. (2005). Firearms laws and the reduction of violence: A systematic review. American Journal of Preventive Medicine, 28, 40–71.

    Article  Google Scholar 

  15. LaFree, G. (1999). A summary and review of cross-national comparative studies of homicide. In Smith, M.D. & Zahn, M.A. (eds.), Homicide: A sourcebook of social research. Thousand Oaks, California.

  16. Land, K. C., & McCleary, R. (1996). Missing time series data and the impact of sentencing guidelines in Minnesota: Can the debate be adjudicated? Criminology, 34, 281–288.

    Article  Google Scholar 

  17. Lee, W. S., & Suardi, S. (2010). The Australian firearms buyback and its effect on gun deaths. Contemporary Economic Policy, 28, 65–79.

    CAS  Article  Google Scholar 

  18. Leigh, A., & Neill, C. (2010). Do gun buybacks save lives? Evidence from panel data. American Law and Economics Review, 12, 509–557.

    Article  Google Scholar 

  19. McCleary, R., McDowall, D., & Bartos, B. J. (2017). Design and analysis of time series experiments. Oxford: Oxford University Press.

    Google Scholar 

  20. National Research Council. (2005). Firearms and violence: A critical review. Washington, D.C.: National Academies Press.

    Google Scholar 

  21. Ozanne-Smith, J., Ashby, K., Newstead, S., Stathakis, V. Z., & Clapperton, A. (2004). Firearm related deaths: The impact of regulatory reform. Injury Prevention, 10, 280.

    CAS  Article  Google Scholar 

  22. Reuter, P., & Mouzos, J. (2004). Australia: A massive buy back of low-risk guns. Evaluating gun policy: Effects on crime and violence, 121.

  23. Rubin, D. B. (1974). Estimating causal effects of treatments in randomized and nonrandomized studies. Journal of Educational Psychology, 66, 688–701.

    Article  Google Scholar 

  24. Rubin, D. B. (2005). Causal inference using potential outcomes. Journal of the American Statistical Association, 100, 322–331.

    CAS  Article  Google Scholar 

  25. Small Arms Survey. (2007). Small arms survey 2007: Guns and the city. Cambridge: Cambridge Univ Press.

    Google Scholar 

  26. Stearns, J. (2015). The effects of paid maternity leave: Evidence from temporary disability insurance. Journal of Health Economics, 43, 85–102.

    Article  Google Scholar 

  27. Ukert, B., Andreyeva, E., & Branas, C. C. (2017). Time series robustness checks to test the effects of the 1996 Australian firearm law on cause-specific mortality. Experimental Criminology (pp. 1–14.

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This research was conducted using publicly available data and did not receive any external support or funding.

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Correspondence to Bradley J. Bartos.

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This type of retrospective study does not involve identifiable human subject data and is exempt from IRB review.

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Bartos, B.J., McCleary, R., Mazerolle, L. et al. Controlling Gun Violence: Assessing the Impact of Australia’s Gun Buyback Program Using a Synthetic Control Group Experiment. Prev Sci 21, 131–136 (2020).

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  • Firearm policy
  • Gun violence
  • Synthetic control group
  • Homicide
  • Suicide