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Gun Violence and Gun Ownership – lets look at the data

By Joshua Tewksbury

After the recent tragic school shooting in Connecticut, USA, I saw a lot of traffic on my facebook site focused either on the need for stronger gun control, or the ineffectiveness of  stronger gun control when it comes to  reducing the likelihood of these kinds of tragedies.  That last bit of the sentence is critical.  Nobody argues that gun control can completely stop all gun violence, but there is a lot of mis-information out there on the link between gun violence and gun ownership, or gun violence and gun laws.  At first I found myself responding to posts by my friends on facebook, making probabilistic arguments based on my own memory of the link between gun ownership and gun violence.  But these arguments get tricky, and so I decided to take a quick look at the data myself.   Country by country data is simplest to work with, so I have stuck to those data.

Gun Violence as a Function of Gun Ownership rates for all countries

The first graph is the relationship between gun ownership (guns per 100 residents) and gun violence (gun related deaths per 100,000 people), across all 75 countries where that data is easily obtainable (see end of post for data sources).  If I were an advocate for gun rights, I might feel pretty good – there appears to be no correlation at all between gun ownership and gun violence among countries.  Here in the United States, we look somewhat remarkable in our capacity to keep our guns in check.  We have loads of guns, and a lot less gun related violence than many countries.  Countries like… El Salvidor, Jamaica, Honduras, Gautamala, Swaziland, Columbia… Hmmm.  These countries are not exactly comparable to the US.  In a perfect world, we’d like to have data on a series of countries that are mirror images to the U.S. in all ways (size, GDP, urbanization, age of country …) except access to guns.  We don’t have that of course, but we get a lot closer by restricting the data to “similar” countries. There are a number of metrics out there we could use to do this. Here I use the UNDP Human Development Index (HDI) as a way of creating a similar set of countries.   The HDI combines data on  life expectancy, education, and income indices to rank countries into four tiers of human development – very high, high, medium, and low.

In the second graph, I restricted the data to all countries in the top  HDI category (Very High HDI [HDI > 0.79]). The picture changes dramatically.   Now we see a clear positive relationship between gun access and gun violence.  The US clearly has the most gun violence and the most guns.  I have fit a linear regression through this data (Adj. R2 = 0.47), and if we think the linear relationship is reasonable to begin with, we could begin to think about why some countries are above the line and others are below the line (for example, the US is considerably above the line, and thus it appear that US citizens not only have more guns per capita, they also have a harder time keeping their guns pointed away from other people compared to  many other countries).  I would not  walk too far down that path without adding a lot more nuance to the analysis.  There are all sorts of things we might want to

Gun Violence as a Function of Gun Ownership rates for countries with a Very High Human Development Index Score 

consider – size of country, % of people living in big cities, etc..  I doubt very much these variables will change the basic picture (more access to guns is positively related to more gun violence, all else being equal), but they would be worth exploring.  All the data used here were taken directly  from public sources, see firearm-related death rates and guns per capita data.
I have to get the kids to school (the strange irony of that one fully realized), but I will post my data file later today, so others can play with the data.   The killings in Connecticut are a tragedy, and I don’t think anyone would argue that we can fully prevent these type of events through gun control laws.  But that is not the point of gun control laws anyway.   We are  seeking to minimize the risk, and reducing access to guns does appear to do this.
If you want to reduce the risk of gun related violence, you can move to a state or a country where gun laws are stricter and cultural norms surrounding guns are more progressive (full disclosure, that is exactly what my family is doing right now, but we did not do it for the gun laws alone [the cheese, chocolate, wine, working trains and high mountains in Switzerland are more of a pull]).  Or, if you can’t or don’t want to move,  you can work to pass stricter gun laws where you live and work to create a more progressive environment around gun use.  There are lots of details that can be argued, but the fundamentals are not so different than other dangerous issues. If you want to reduce smoking, you make it harder and more expensive to smoke. Nobody seems to argue with that logic. At a very basic level, I am not sure why this this wold be any different. We know we can’t stop every wacko from harming others, we just want to reduce the percentage of wackos that have guns!
UPDATE  Dec 20h, 5:51 AM:  Data for this graph and related graphs on the next post are taken from the following websites:
The raw data are also available through the next post.  On that post, you can also find an updated graphic, with the UK included (missing due to a data-error in this graph).

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