Existentialist Requiem: 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