# Guns per Capita and Homicides – Is There a Correlation?

Here’s a statistics quicky. A while ago, just after the tragic shooting at Sandy Hook Elementary School, I wanted to produce a clear proof that gun ownership and homicide rates are correlated. It seemed logical to me that, plus / minus statistical fluctuations, the phrase “more guns, more violence” holds true. So I extracted the relevant data for all first world countries from Wikipedia and did the plot. Here’s the picture I got:

Maybe you are as surprised as I was. Obviously, there’s no relationship between the two variables, more guns does not mean more violence and less guns does not mean less violence. So whatever the main cause for the violence problem in the US (see the isolated dot in the top right? That’s the US), it can’t be guns. And that’s a liberal European speaking …

Just in case anyone cares, I blame the gang and hip-hop culture. I can’t be guns (see above), but it also can’t be media or mental health or drugs (people in all other first world countries also play shooter games,  watch violent movies, have mental problems, buy and sell drugs).

Sources:

http://en.wikipedia.org/wiki/Number_of_guns_per_capita_by_country

http://en.wikipedia.org/wiki/List_of_countries_by_intentional_homicide_rate

1. Great post. I’d have to agree with your conclusion, though I’m not sure how I (or anyone) could accurately measure it…

1. Hey Sam, thanks for the comment! Yes, the influence of gang culture is unfortunately impossible to quantify, so I can only assume it to be a main factor using the exclusion principle but not proof it.

1. Good point. I suppose the exclusion principle accurately says (in this case) that there is some exogenous factor, prevalent in the United States, that is associated with an inflated homicide rate and is not explained by the model. I can’t imagine someone offering a viable candidate for said exogenous variable other than gang culture. I’ve seen a lot of research about income inequality and violence, but despite rhetoric amongst political pundits, politicians, and groups like Occupy Wall Street, income inequality (as measured by the Gini Coefficient and ratio of income of top 10% to bottom 10%) really isn’t all that high. Well, it’s high and it’s obvious that income inequality exists, but not so high as to suggest that it’s responsible for what’s seen in the model. Countries like Chile, South Africa, and Argentina have much higher income inequality, for example, and inequality is only a bit more prevalent in the U.S. than in Australia or The UK. So, yes, it’s an issue, but it doesn’t seem like it’s a viable candidate either.

Keep up the great posts! Really thought-provoking and well done. I’m still getting used to this blogging thing lol.

2. “Gang culture.” I’d like to see a definition. Does it include “white males with means” as a “gang”?

3. Hypergeometric –

It seems you think I said something that wasn’t ‘politically correct’, so let me explain what I meant by ‘gang culture’. Linked below is how the government and various entities sponsored by universities attempt to define gangs:

http://www.fbi.gov/stats-services/publications/2011-national-gang-threat-assessment

http://libguides.luc.edu/Chicago_Gangs

Also, “Gang Leader for a Day” is a great book, written by a UChicago grad student, about gangs:

Anyway, I’m referring to street gangs, though I’m not sure of a precise definition. I was thinking specifically of gangs that originated in Chicago (since I live here and gang signs/colors/etc. are prevalent near the college I attend), such as the “Black P Stones” (membership: 30,000-42,000), the “Latin Kings” (membership: 20,000-35,000), since a considerable amount of violent crime in Chicago is associated with gang activity.

But in response to your question about whether white males with means constitute a gang – yes, they could. There are plenty of white supremacist gangs, most of which are motorcycle gangs – the Outlaws, Pagans, and Mongols are examples – that generate a lot of money from trafficking meth and cocaine. Also, the ‘Black’ in ‘Black P Stones’ doesn’t mean that members are exclusively black – there are latin, white, and arab members, among others. The same goes for the Latin Kings – most are Latin, but it’s not a hard-and-fast rule.

Forgive my disregard for political correctness, but, first, I don’t think I said anything offensive and, second, living in a bad part of one of America’s most violent cities has made me insensitive to the fluffy political buzzwords that pundits use to describe gang violence.

2. It would be interesting to do the same plot, assuming the data were available, for the top N cities of the United States. Bureau of Justice Statistics? CDC also has a (better) tabulation of homicides by guns. This would let us check $P(\text{guns per capita and homicides}|\text{country}=\text{United States})$.

1. Hello Jan, thanks a lot for the helpful comments! I agree, it would be very interesting to see this plot for the US states, I’ll be sure to check out the links you provided and see what I can cook up from these. Have a nice day!

3. @Samchappelle,
Thanks for your reply. I wasn’t at all concerned about “politically correct” anything. I was simply asking for a crisp definition of something which needed to be measured. I did not think, in your post of August 24, 2013 at 1:40 pm, you were actually talking about street gangs but, rather, some kind of wider cultural phenomenon in order to explain the United States as outlier. I know the author said “Just in case anyone cares, I blame the gang and hip-hop culture.” However, unless white suburbia is embracing such culture, it is not a compelling explanation for gun homicides there. According to circumstances of killings, gang-related murders just don’t explain it: http://www.fbi.gov/about-us/cjis/ucr/crime-in-the-u.s/2010/crime-in-the-u.s.-2010/tables/10shrtbl10.xls

Also, I would take exception to the author’s conclusion that because no other countries show the correlation, the prevalence of gun ownership cannot be an explanation in the United States. After all, the density of gun ownership, according to the figure, is 50% higher than the nearest other country. The figure does not have a lot of statistical relevance or power, and needs to be broken out more carefully. If I were doing the study (which I won’t: I’m not interested in it that much) I would break it out as conditional morbidity by firearm rates, that is, map the density of firearm morbidity across various spatial densities, like per capita income or density of non-violent crime, and things like that.

In my experience, “surprises” arise because of a poorly framed question.