Friday, July 27, 2012

Guest Post - On shootings and firearm statistics

The following was written by the Evil Dr. Pain and originally posted on facebook Wednesday, July 25th.

On shootings and firearm statistics

Following the recent atrocity in Aurora, the latest in a sadly growing list of gun-related attacks on groups of the public (for which the US is growing increasingly infamous), there has been the expected surge in arguments between the pro-gun and pro-gun-control lobbies. Regrettably, a large portion of this argument has either been from people voicing opinions in the same tired catch-phrases or variants thereon (the various versions of "guns don't kill people, people kill people", for example), usually without anything substantial to support their argument, or a neverending sequence of memes telling us the same things, disguised in cheap derivative humour. Sure, this is Facebook, and is a great vehicle for generic siliness (A little nonsense, now and then, is relished by the wisest men...), but when it comes to matters as grave as this, I hope we can put this aside and have a serious discussion about the issues.

The central question in discussing these issues must surely be: Just how dangerous are guns, on a societal level? We understand intuitively in individual cases - common sense tells us that a gun in responsible hands is no significant social danger, and a gun in the hands of the wrong person can be a terrible danger (these are the foundations of the arguments from the pro-gun and pro-gun-control camps, respectively) - but an answer requies not simply the consideration of the extreme cases, but the vast majority that lie between. The obvious thing to do is to look at some data.

Here, I'm focussing on gun crime only (ie excluding firearm accidents, suicides etc). Gun crime is quite a complicated issue, as it is tied to numerous variables, many of which hard to quantify (or even identify qualitatively). Consequently, the best this represents is a zeroth-order pass at considering gun crime statistics from a nation-by-nation standpoint.

The data

All data I've plotted here are sourced from the United Nations Office on Drugs and Crime and theSmall Arms Survey, and can be found at this article in the Guardian. The data are far from complete (many developing countries are missing, along with Russia and China), but cover a significant fraction of the world, including most of the developed world, and thus shed light on some general trends.

For all plots I generated, data points in blue are the entire "global" data set. Because many of the factors which influence gun crime (and crime in general) are social factors which are hard to quantify (as yet, I've not included any quantitative metric for them), I've labelled a selection of countries in each plot, in order for the viewer to illuminte the data with their own social and political knowledge. For each plot, I've included an inset of an unlabeled plot, so that the distribution of the data may be seen without the distraction of overlaid text. Furthermore, in an attempt to clarify the effects of the varibles plotted, I've taken a subset of the data (plotted in red), labelled "Western World". This selection of countries roughtly represents the "First World" (Western Europe, USA, Canada, Australasia, Japan and South Korea) - countries which are relatively similar in social and political terms (on a global scale). Plots of only these data are discussed following the discussion on global data.

Global data

Fig 1 - Firearm homicide rate vs number of firearms per capita

Fig 1 shows the firearm homicide rate (per 100,000 people, per year) against the prolificity of firearms (guns per 100 people). It is immediately clear is that there is no correlation between these two raw varibles. This is perhaps unsurprising, as any underlying correlation between the availablity of firearms and the homicide rate is bound to be lost in the numerous social factors impacting on crime rates. The extent to which the US is a global outlier is clear here; it has the highest number of guns per capita of any country, by several standard deviations from the norm. On a global scale, its firearm homicide rate is low (especially considering the prolificity of firearms), although the countries dominating the firearm homicide rate are not First-World countries, and most have significant social/political problems. The First-World countries in red have a vastly lower firearm homicide rate than the global average.

Fig 2 - Total homicide rate vs number of firearms per capita

Fig 2 shows the total homicide rate (per 100,000 people, per year) against the prolificity of firearms (guns per 100 people). There's is no real correlation between these two raw varibles, for the same reason as before. Again, the First World countries in red have a vastly lower homicide rate than the global average, and the US lies at between the First World and the remainder of the globe.

Fig 3 - Percentage of firearm homicides vs number of firearms per capita

Fig 3 shows the percentage of homicide that involved firearms against the prolificity of firearms. Surprisingly here, there is not obvious correlation between these variables, and in this case the first world countries and are more evenly ditributed with the rest of the globe. Overall, the fraction of firearms involved in homicidal behaviour seems independent of the availability of the firearms.

Fig 4 - Firearm homicide rate vs total homicide rate

Fig 4 indicates the strongest correlation in the data; the firearm homicide rate as a function of the total homicide rate. The correlation is positive, and is well desribed with a quadratic term (plot to follow), indicating that the more violent a country is, the more guns are involved in the murder rate.

Fig 5 - Percentage of firearm homicides vs total homicide rate

This is demonstrated in Fig 5, which plots the percentage of firearm homicides against the total homicide rate. Here, a group of very violent countries can be seen to have a separate grouping (distinct from much of the world, including the first-world countries) with distinct positive correlative trend. Curiously, in this parameter, space, the USA lies at the cusp between the most violent, troubled countries, and the rest of the world.

The 'First' (or 'Western') World data

In examining the first world countries (in the plots, labelled "Western World"), we are able to examine data for which the distribution of social and political factors is much smaller (all the countries herein are relatively wealthy democracies), more clearly illuminating any correlations between plotted variables. In all these plots, it can be seen how much of an outlier the USA is compared to the rest of the First World.

Fig 6 - Firearm homicide rate vs firearms per capita, for the First World

Fig 6 shows the firearm homicide rate against the number of guns per capita, for First-World countries. Unlike Fig 1, where any correlation was lost in the vast variation in social and political factors, here was can see a direct positive correlation. Though there are still considerable variations in the data, it can clearly be seen that in the democracies of the First World, having more guns directly correlates with more people using them to shoot people. 

Fig 7 - Firearm homicide rate vs total homicide rate, for the First World

Fig 7 shows the firearm homicide rate against the total homicide rate for the First World. Though here there is more scatter than for the global data (Fig 4, dominated by the more politically/socially troubled  countries), there is some evidence for a positive correlation between the firearm homicide rate and the total homidide rate(ie the more people are killing each other, the more they are shooting each other).

Fig 8 - Total homicide rate vs firearms per capita, for the First World

Fig 8 shows the total rate of homicides against the number of firearms per capita, for the First World. In these data (excluding the USA datum), it is difficult to say if there is any correlative effect at all between the total rate of homicides and the number of firearms per capita (though with the USA point, it is not difficult to imagine a quadratic trend).

Thoughts on the data

On examining the data, it is probable that, though the prolificity of firearms appears to have an impact on the number of firearm-related homicides in the First World, it probably has little impact on the total rate of homicides. That is, having fewer guns around does not make you safer from being killed, but it does make you safer from being shot.

If, however, the number of guns in the US is not the major factor driving the homicide rate, it clearly is true that the number (and nature) of guns in legal circulation directly enables the large-scale firearm massacres, of which Aurora was the latest. Of course, whilst these massacres are very high profile, they contribute very little to the total statistics. The Aurora death toll was about 0.08% of the homicide toll for the US in a typical year. Twice as many people are shot to death daily in the USA (and almost four times as many homicides in total are committed daily) as were murdered in Aurora. Despite the fact that these events contribute so little to the total homicide rate in the USA, it is necessary that they be so strongly focused upon. There is something disturbing about the complete lack of discimination involved in such acts. There is something disturbing about the sheer magnitude of death an injury. They are a canary for social health. 

Returning to the data above, it is clear that the USA is a considerable outlier with repect to the remainder of the First World in almost all parameters. The percentage of firearm-related homicides is the exception, in which the USA actually does statistically well compared to other nations, considering how many firearms are around in the USA.  However, the fact that the USA does considerably worse in terms of homicidal statistics compared to the rest of the First Worldsuggests a significant social factor, which drives its homicide rate (gun-related and otherwise).

The irony, then, of this study is that the focus in the wake of such attrocities should not be solely on firearm control (which of course could help limit the ease with which these major atrocities can be conducted; most sociopathic lunatics are hardly well set to make easy in-roads with black-market dealers), but on identifying and correcting the underlying social problems which stand in the way of the USA reaching its full potential as a civilised (meaning full of civilians, who are able to live without feeling the need to be armed) member of the First World.

Wednesday, July 4, 2012

What it means - and what it doesn't

(from the front page of today's

You may have heard by now... researchers at the ATLAS and CMS experiments at CERN have announced today that they've discovered the God Particle. I wasn't surprised by the announcement, but I did come home from my morning run to find text messages from family members asking for explanations.
First off, let me point out that the researchers themselves are, while excited, much more hesitant to refer to the announcement as revolutionary. The media has made a run of it, but not the scientists themselves.
So what does it mean?
In the Standard Model of particle physics, the best understanding we have to date of the subatomic world, the Higgs field was predicted decades ago to be the mechanism by which other particles have mass (think of wading through a river with your clothes on - the farther across you get, the wetter the fabric is and the heavier you are because of it). In our understanding of the universe, every field is associated with a particle (in more technical terms, the particle is basically a bunched-up bit of the field), so the Higgs field has to be associated with a Higgs boson, and the Higgs boson has to have certain characteristics. And while this Higgs particle is important, and a key feature of the Standard Model, it's not really anything like a "God particle." It's one more piece in the puzzle, one more particle in the Standard Model pantheon.
Now, to the "discovery" of today's announcement. Aside from noting that discovery of the Higgs is not the be-all-end-all of science (what about dark matter? dark energy? unification of gravity with the other fundamental forces?), the data presented today needs to be taken with some hesitation. While the term often thrown around is "five sigma" - meaning that the signal has about a one in a million chance of being just noise - the CERN announcement and the associated figures doesn't show any individual 5-sigma data. That certainty of discovery only comes when taking all of the data together. The fact that CMS, ATLAS, and the Tevatron data from before the shutdown all seem to indicate a new particle in this particular mass region is convincing, though.
But what precisely was discovered? Here's another trick that the media are playing on you. The CERN (and Tevatron) researchers didn't discover the Higgs particle. What they discovered was an as-yet unknown particle with a mass of about 125 GeV. It could be the Higgs. It could be something completely different. What's necessary now is to go through as much data as possible to determine whether the new particle behaves like we theoretically expect the Higgs to behave. Does it have all the right characteristics? We don't know yet. We know that we've looked elsewhere and not seen anything, and we know that in this particular region the data look promising. But that's all.
So what does it all mean? The take-home message is this: they've found something, and it's pretty convincing, but nobody knows for sure what it is. And even if it is the Higgs, it's not the end of science.