Sunday, December 16, 2012

How Not to Debate Gun Control

In the wake of Friday's shooting rampage at a Connecticut elementary school that left 26 dead (not counting the shooter), 20 of them between the ages of six and seven (casualty list here; keep a full box of tissues handy if you decide to read it), there are once again calls for a debate on greater gun control in the U.S., and protests by those against it. I have my own opinions on the issue, which I will keep to myself because they are just that: opinions. Both sides of the issue are repeating a pattern of "debate" that contains several fundamental flaws.

Emotional Decisions

First, both sides are confronting a very difficult issue while emotions are running high. It is hardly surprising that a considerably body of research has shown that emotions impact decision-making in a variety of ways. While there may be some benefit to a heightened emotional state in this case -- it pushes us to take up a contentious issue when we might otherwise be tempted to "kick the can down the road" -- there is also the danger that we let those emotions trump reason. In particular, listening to one's "gut" is considerably easier than dealing with a complex, multidimensional analysis.

Reliance on Anecdotes

There is a rational analysis of the issue on Randy Cassingham's blog, along with a considerable discussion in the comments section. It illustrates the flaws I'm discussing here, including in particular the reliance on anecdotes as opposed to statistics and decision models. Some parties in favor of tighter control over guns and ammunition will argue that, had those tighter controls been in effect, this particular incident would have/might have been averted, or at least produced a lower body count. Some parties opposed to tighter controls (or opposed to tighter controls merely in reaction to this incident) will argue that other crimes of a similar nature were conducted without the use of firearms, citing in particular the 1927 Bath Township school bombings. (It happens that I live approximate four miles from Bath Township.) Both sides are relying on historical anecdotes.

Mr. Cassingham mentions closures of mental hospitals, and some commenters echo the theme that we need to address mental illness, rather than gun control. It's not clear what prompted those comments, other than what I suspect is a common assumption that you have to be nuts to murder children, but it is possible that some people are recalling previous incidents in which they believe a shooter was mentally deranged (in the clinical sense) and either was denied treatment or should have been (but was not) involuntarily committed to treatment. For what it's worth, the shooter in the Virginia Tech massacre had been diagnosed with an anxiety disorder (which, to the best of my knowledge, is not a know precursor to violence) but had been receiving treatment. Eric Harris, one of the two Columbine shooters, also suffered some emotional issues but was receiving treatment. The gunman in the 2006 Amish school shooting seems to have been (in unscientific terms) a whack-job, but an undiagnosed one.

In any case, making decisions based on anecdotal evidence is unsound. Anyone in operations research (or statistics) knows that a sample of size 1 is not a useful sample. Reliance on anecdotes also makes us more susceptible to confirmation bias, since (a) we better remember the anecdotes that support our beliefs and (b) we may unconsciously warp those memories if they would otherwise not provide confirmation.

There's a parallel here to the climate control debate. Elements in favor of climate control legislation will argue that a particular weather event (the North American drought in 2012, "Superstorm" Sandy) was the direct result of global warming, even when climatologists are scrupulous in pointing out that there is no direct causal link to a single event. Global warming naysayers will focus on specific events (recent drops in recorded temperatures, record floods from a century or more ago) as evidence that global warming is not occurring, is not a recent phenomenon, or is not exacerbated by man-made emissions.

Optimizing vs. Satisficing

Not that I really believe "satisficing" is a word, but I'll bite the bullet and use it here. Even when a problem has an optimal solution, it is sometimes the case that the time and effort to find it are not adequately rewarded when an alternative solution provides an adequate degree of satisfaction in a more timely or economical manner. Besides the anecdotal aspect, Mr. Cassingham's emphasis on the Bath bombings and the wave of school stabbings and bludgeonings in China (echoed by some of the commenters) implicitly uses the line of argument that if we cannot prevent every mass shooting by enhanced gun control (optimality), it is not worth pursuing. Many (including, I'm willing to bet, Mr. Cassingham) would consider a reduction in mass shootings, or even a reduction in the body counts, as a significant improvement (satisficing). Gun control advocates are not immune from this focus on optimality; they sometimes appear to adopt the position that any level of regulation that would fail to prevent a particular incident is insufficient.

Multi-Criteria Decision Analysis

Okay, you knew this post eventually had to tie back to operations research in some meaningful way (didn't you?). The issue of how to mitigate violence at schools seems to me to be a rather messy example of multi-criteria decision analysis. This is by far not my area of expertise, so I'll keep things rather general here. As I understand MCDA, the discussion we should be having should be framed approximately as follows:
  • What are our criteria for success? This includes a variety of objectives: keeping children safe; preserving individual rights; making schools conducive places for learning; maintaining a populace capable of defending itself in times of war (I personally do not subscribe to the theory that gun owners necessarily make more effective soldiers, but it should be considered); and likely other objectives I'm not seeing at the moment.
  • How do we quantify/measure attainment of those objectives? For instance, it's fine to say we want no more children to die at school (or perhaps no more deaths specifically from gun violence), but does that mean that a 99% reduction in such deaths has no value? What about a 1% reduction?
  • What are our options? We cannot have a meaningful argument about choices without knowing what those choices are.
  • What are the costs and consequences of each alternative? These will need to be considered in a probabilistic manner. To take a specific, if rather vague, example, suppose that one of the options bans the sale of high-capacity ammunition clips. That would not stop a shooter from wreaking havoc with one or more standard clips, nor could we be positive that no shooter ever would manage to gain access to a high-capacity clip. For that matter, we have no idea when another school shooting might take place (although, sadly, the "if" does not seem to be in doubt -- see the Wikipedia compilation of school-related attacks for some severely depressing historical evidence.). Someone will need to attempt a quantitative assessment of the frequency and severity of violent incidents under each alternative being considered. "Minority Report" being a work of fiction, we cannot claim that a particular decision will prevent or mitigate a specific future attack; we can only talk about expected benefits (and costs).
  • If we consider multiple alternatives in combination, how do they interact? There is no reason to assume that, in our quest to make life safer for our children, we are limited to a single course of action. It would, however, be a mistake to evaluate each course of action independently and then assume that the results of a combination of them would be additive.
  • How will we reconcile trade-offs? As one can see in the Wikipedia article on MCDA, there are quite a few methods for solving a multi-criteria decision problem. They differ in large part in how they address the issue of trade-offs. For instance, charitably assuming we can even measure these things, how much freedom are you willing to give up, and/or how much more are you willing to pay in taxes, to eliminate one "expected" future fatality or injury?
This is all very complex stuff, and to do it justice requires a great deal of research (by unbiased parties, if we can find them), a careful and open discussion of what we might gain and what we might lose with each possible action, and an attempt to reach consensus on what trade-offs are or are not acceptable. If the process ever reaches a conclusion, it will also take one heck of a sales job to convince the public that the result really is a good (not perfect, but better than status quo) result.


Shivaram Subramanian wrote a really interesting and well-researched "Collection of Notes on Gun Control", which I commend to anyone interested in the debate. (You won't often see Louis L'Amour, Isaac Asimov and King Asoka of India name-checked in the same blog post.) He cites a Washington Post column from July, in the aftermath of the Aurora (Colorado) shooting, titled "Six facts about guns, violence and gun control" which is also very much worth reading (or, sadly, rereading).


  1. very timely piece of writing. thanks.

  2. I would like you to take a look at this graph

    Notice the empty right quadrant?

    1. Thanks. I think that this graph and several related ones can be seen at (except that, as I post this, the site is unavailable due to bandwith limit).

  3. Very nice article Paul. Well written. I do appreciate how you wrote the article from an unbiased perspective. I for one am against stricter gun control. My reasons aren't important as I can argue them with gun control advocates all day and provide studies such as the one from Harvard that analyzed gun control in Western Europe in relation to violent crime rates and still get nowhere. I think emotional decisions are being made that in the end will not protect anybody any more then existing laws already do. Enforcement, access to mental health facilities, and less blaming everything on guns.

    1. Thanks, Cameron. I'm pretty sure you and I will find ourselves on opposite sides of the gun debate, although my views are not fully formed. Both sides can produce statistics, charts and studies, but I'm not sure the interpretation of them is always on point. I also think there are important questions for which data has not yet been analyzed (at least I've not seen any analyses in print). Perhaps most importantly, because both sides are emotional, the debate fairly quickly devolves into something close to ban all guns vs. no regulation whatsoever, and opportunities for meaningful compromise are missed. We'll never stop all crimes of violence (unless we manage to depopulate the planet, which I don't rule out, especially since today is Mayan Extinction Day), but I think we can reduce some amount of it -- by a variety of measures, including but not limited to gun (or ammo) control.

  4. Your points regarding rational decision making are certainly well-taken. I’m not optimistic however, given the current social and political climate in the U.S., that we have the wherewithal to approach the gun control/gun rights decision rationally and deliberately. At times, it seems the only way any decision gets made is emotionally, in the heat of the moment.

    In that regard, I found a December 18 New York Times editorial on the Newtown shootings and subsequent political responses interesting. Their point seems to be largely akin to Rahm Emanuel’s admonition not to let a good crisis go to waste – and they argue forcefully that we should follow our gut to enact needed gun control reforms ASAP.

    The Times’ position is not surprising. Their own words however, drove home for me the potential downside in making hasty, emotional decisions in the face of a tragedy. They point to the country’s willingness to make sacrifices in a crisis: “Americans are ready to shoulder burdens — as we did after the Sept. 11, 2001, attacks by accepting increased security when we travel and military actions we might previously have avoided.”

    Were these burdens appropriate ones to accept in the wake of 9/11? Have they been effective? If so, at what cost? With eleven years of hindsight, would we support the same decisions?

    1. I don't recall "accepting" increased security when I fly; I seem to recall having it imposed on me. It's somewhat better of late, in that I get a free MRI every time I pass through an airport.

      I think you (and Rahm Emanuel and the Gray Lady) are right that we need an emotional push to get us past the usual yack-yack-deadlock-repeat cycle. Maybe the best thing is for the current emotional surge to get a non-/bi-/multi-partisan commission formed to come up with proposals, the commission to be staffed by relatively analytical and relatively level-headed types. Then again, we tried that with the Simpson-Bowles commission, and that's worked out just peachy so far.


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