Thursday, 20 December 2012

Gun Ownership and Gun Deaths

It seems intuitively obvious to me that deaths by firearm would increase according to availability of firearms, and the prevalence of gun crime in the United States appears to bear this out. But that is just one data point; do the statistics bear this out?

Well I'm no statistician, but I can just about use Excel, so here's the developed countries culled from this list and plotted:

A trend emerges, though it's a lot less emphatic without the US:

Here's the dataset:
Country/Territory Homicide by firearm rate per 100,000 pop Average firearms per 100 people
Australia 0.14 15
Austria 0.22 30.4
Belgium 0.68 17.2
Canada 0.51 30.8
Denmark 0.27 12
England and Wales 0.07 6.2
Finland 0.45 45.3
France 0.06 31.2
Germany 0.19 30.3
Greece 0.26 22.5
Ireland 0.48 8.6
Israel 0.09 7.3
Italy 0.71 11.9
Netherlands 0.33 3.9
New Zealand 0.16 22.6
Norway 0.05 31.3
Portugal 0.41 8.5
Spain 0.2 10.4
Sweden 0.41 31.6
Switzerland 0.77 45.7
Turkey 0.77 12.5
United States 2.97 88.8

It's interesting that the US makes quite a difference, but then it is currently that anomaly (gun crime in the States) that we are trying to explain, given the dreadful events at Sandy Hook. Nevertheless, it should be noted that there are difficulties comparing countries like this.

A review of the literature 1 a few years back, however, does conclude that gun deaths and gun ownership are correlated, while noting my proviso:
4. Conclusion
The available evidence is quite consistent. The few case control studies suggest that households with firearms are at higher risk for homicide, particularly firearm homicide. International cross-sectional studies of high-income countries find that in countries with more firearms, both men and women are at higher risk for homicide, particularly firearm homicide. This result is primarily due to the United States, which has the highest levels of household ownership of private firearms, the weakest gun control laws, and the highest homicide rates. Time series studies of particular cities and states, and for the United States as a whole, suggest a positive gun prevalence-homicide association. Finally, perhaps the strongest evidence comes from cross-sectional analyses of U.S. regions and states. Again, places with higher levels of gun ownership are places with higher homicide rates.
None of the studies can prove causation and none have completely eliminated the possibility that the association might be entirely due to reverse causation or omitted variables. But the available evidence is entirely inconsistent with the hypothesis that increased gun prevalence lowers the homicide rate. Instead, most studies, cross sectional or time series, international or domestic, are consistent with the hypothesis that higher levels of gun prevalence substantially increase the homicide rate.
The comparison across US States apparently providing the strongest evidence. It would be interesting to see some more literature reviews; it's interesting reading about the difficulties in data comparisons across diverse countries and regions - cultural differences and data collection methods must affect the data significantly. Nevertheless, the consistency in the results, leaves us confident in concluding there is a correlation (note the causation caution above) between gun ownership and gun deaths, which suggests reducing gun ownership might well result in a decrease in gun deaths, which is in line with my intuitions, at least.

1 Lisa M Hepburn, David Hemenway, Firearm availability and homicide: A review of the literature, Aggression and Violent Behavior, Volume 9, Issue 4, July 2004, Pages 417-440, ISSN 1359-1789, 10.1016/S1359-1789(03)00044-2.
Keywords: Firearm; Firearms; Homicide; Guns


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