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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.


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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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The publicly available data used in this study consists of aggregate frequency counts at the nation-level, and contains no individual or group level identifiers. For this type of study formal consent is not required.

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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