Saturday, December 5, 2015

11,300 guns = 1 human life

I was sifting through the data that was available on Wikipedia on guns per capita and gun deaths per capita.  Found that among the countries with the top 15 scores for Human Development Index, the correlation between guns owned and gun deaths per capita has an R2 of 0.94.



Using this line of regression, you might even say that, in a highly developed country, the optimal number of firearms per 100 people is the y-inercept of this line, at 5.61 guns or fewer per 100 people.  US has the 5th highest HDI, making it one of the world's most developed countries, so it falls squarely in this category.

Above that optimal number of guns, the line of regression shows that there is about 1 death for every 11,300 guns in a highly developed country.  In other words, if we had a gun buyback program, for every 11,300 guns that were turned in, 1 human life will be saved.

The correlation between guns and deaths becomes weaker as you start to include countries with progressively lower HDI.  But the correlation was still strong at R2=.75 for the top 33 countries Wikipedia had the relevant data on.  This line of regression, which has a less strong correlation, suggests that the optimal number of guns is zero (since you can't have a negative number of guns), and above that, 1 human life is lost for every 12,900 guns owned.  Still in the same ballpark as before.



Note that the US falls just above the line of regression in each case, suggesting that this relationship holds true for us as well.

Here's the data used to construct the above graphs, all taken from Wikipedia on December 5, 2015:

Country HDI (Human Development Index)
HDI Rank
Guns/100 (2014)
Gun deaths/100,000/year
Year of Calculation
Norway 0.944 1 31.3 1.78 (mixed)
Australia 0.933 2 21.7 0.86 -2011
Switzerland 0.917 3 45.7 2.91 (mixed)
Netherlands 0.915 4 3.9 0.46 -2010
United States 0.914 5 112.6 10.5 -2013
Germany 0.911 6 30.3 1.24 -2010
New Zealand 0.91 7 22.6 1.45 (mixed)
Canada 0.902 8 30.8 2.22 (2007-2011)
Singapore 0.901 9 0.5 0.16 (mixed)
Denmark 0.9 10 12 1.28 -2011
Sweden 0.898 12 31.6 1.47 -2010
Iceland 0.895 13 30.3 1.57 (mixed, incomplete)
UK 0.892 14 6.6 0.26 -2010
South Korea 0.891 15 1.1 0.06 (mixed)
Japan 0.89 17 0.6 0.06
(mixed)
Israel 0.888 19 7.3 1.87
-2009
Taiwan
0.882 20 4.6 0.87
(mixed)
France
0.884 20 31.2 3.01
-2009
Luxembourg
0.881 21 15.3 2.02
(mixed)
Belgium
0.881 21 17.2 2.42
-2006
Austria
0.881 21 30.4 2.95
(mixed)
Finland
0.879 24 29.1 3.64
-2010
Slovenia
0.874 25 13.5 2.49
(mixed)
Italy
0.872 26 11.9 1.28
-2009
Spain
0.869 27 10.4 0.62
(mixed)
Czech Republic
0.861 28 16.3 1.76
-2010
Greece
0.853 29 22.5 1.64
(mixed)
Qatar
0.851 31 19.2 0.15
(incomplete)
Cyprus
0.845 32 36.1 0.96
(mixed)
Estonia
0.84 33 9.2 2.54
-2010
Poland
0.834 35 1.3 0.25
-2010
Slovakia
0.83 37 8.3 1.75
-2010
Portugal
0.822 41 8.5 1.77
-2010

Sources:

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