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De-Obfuscating the Statistics of Mass Shootings
- aftbit 11y agoInterest groups lying with statistics is a specific example of confirmation bias. It's sadly so prevalent that I generally assume that any statistics I find are intended to lead me in a particular direction. I am skeptical of the final implication of the blog entry, that improved gun-safety legislation would solve this issue. For someone taking such a strong approach to statistics, it's a shame that they focus on only one facet of such a complicated situation. American culture, mental health treatments, social programs, and gun laws are all different from most other countries on their list - it seems disingenuous to mention only the last.
- ta92929 11y agoI know this is just pissing in the wind (and you just used the term from the article), but "gun safety" already means something. <https://en.wikipedia.org/wiki/Gun_safety> https://en.wikipedia.org/wiki/Gun_safety> This type of language engineering annoys me.
- apolretom 11y ago"This article disagrees with my priors, therefore it is wrong."
- vanderZwan 11y agoThe blog concludes that the abuse of statistics is politically motivated by a vested interest in keeping gun-safete legislation minimal. This is not the same as implying that there should be more gun-safety legistation.
- kromem 11y agoYour comment is actually a perfect example of why I have issues with using per capita as the basis of the analysis. I adjusted the OCED numbers to be on a per-gun basis as opposed to a per capita basis and non US OCED countries combined were more likely to have rampage shootings per gun than the US. There are not issues in the US with social programs, mental health, etc as compared with other countries when looking at mass shootings. The only number that plays any significance is the number of guns per capita to influence the number of shootings per capita. If other countries had as many guns per person as the US, the data indicates they'd proportionally have the same amount of shootings per person or more.
- lagadu 11y agoThe problem here is that you're assuming there's a correlation between guns per capita and shootings per capita, which is similar to the (potential) fallacy that the OP made: that there's a correlation between gun restriction laws and shootings per capita.
- res0nat0r 11y agoWhy is the USA then the extreme outlier then when it comes to the sheer number of shootings also highest concentration of guns anywhere in the developed world?
- tedunangst 11y agoPerhaps people afraid of being the next shooting victim buy lots of guns.
- LyndsySimon 11y agoI have a lot of guns, and I know lots of people with lots of guns. None of us buy them beause we're "afraid of being the next shooting victim".
- tedunangst 11y agoAh, so per resonators comment, you must have bought them because you want to be the the next shooting perpetrator.
- hga 11y agoCorrelation does not imply causation. As noted elsewhere in this discussion, there are plenty of other potentially relevant correlations, and as also noted, if you cast the net wider than the ODEC we no longer are an "extreme outlier".
- res0nat0r 11y ago
- eli_gottlieb 11y agoUnless social programs turn out to be unexpectedly cheap or gun law enforcement unexpectedly expensive, gun laws are probably the cheapest, smallest-delta intervention against mass shootings.
- hga 11y agoGun control cost the Democratic party control of the Congress in 1994 and the Presidency in 2000. That's about as "expensive" as policies get in the US.... And as noted in this discussion, any attempt to squeeze tight enough that there might actually be an effect on mass shootings of the current type would replace them with fantastically more "mass" shootings of the civil war type, which tend to be only exceeded by foreign invasions as "expensive".
- vacri 11y agoSpree killings/mass murders/rampage shooters/whatever are all a canard anyway. A canary in the coal mine. Add up all the spree killers in the US and they'll not break 1% of the murders. Just like the debate over automatic weapons is a canard, since they're very rarely used in murders. The US has a murder problem. It's murder rate is four times that of it's industrialised contemporaries. Most of those murders (~75%) are done with firearms, and most of those (>75%, can't recall exactly) are done with handguns. And by someone who knows the victim closely. The stereotype of the inner-city gangsta gunning down a gangland enemy with an automatic weapon is an outlier. And the same is true of the spree killer. As long as debates on either side center on these kinds of outliers, little will be achieved. The murder rate isn't going to be affected by open carry, since most murders aren't of strangers. And banning automatic rifles isn't going to do anything either, because it's handguns that do the dirty work. The problem is that these details aren't sensationalist. Being gunned down by a stranger on a rampage makes the news. Being killed by a crazy relative doesn't.
- 15155 11y ago> because it's handguns that do the dirty work I'd also like to point out that the Supreme Court of the United States of America affirmed that individual ownership of semi-automatic handguns (cited example, but, "common use" is the test) is a protected right. We have a financial inequality and mental health problem (somewhat stemming from said inequality) in this country, not a firearm problem. These are the problems that need addressed to reduce crime.
- x0x0 11y agoThe justices, as aptly demonstrated recently (viz scalia, whose textualism has no meaning besides whatever his personal politics prefer) are politicians, no more. Or one could ask why gay rights have done better than reproductive rights, and the answer comes down solely to Kennedy is more sympathetic. At this point, we are so inured to gun violence that my SO was at a community college a couple years ago while it had a lockdown because of a shooter on campus. She was ushered into a classroom by swat with them standing outside the door and it didn't even make the tv news that night. I grew up shooting guns with my father and have treasured memories of going to gun shows. I'd vote for an amendment for Japanese gun laws. ps: in 2008, the us had 12k+ firearm related homicides while japan had 11. The population ratio was 2.39, so the US would have experienced (rounding up) 27.
- caf 11y agoI believe the statistical lesson here is widely applicable, and may well be of use if data analysis - particularly of rare events - is part of your job.
- praptak 11y agoThis statistical lesson is actually a textbook error, similar to taking a p=0.05 test on multiple subjects separately. What makes this interesting is the political context.
- kromem 11y agoIt's disingenuous to compare shootings purely by a per-capita basis. It should be per-capita among gun owners. The data as shown indicates the US has a cultural mass shooting phenomenon, but it's simply not accurate. The US just has more guns, and mass shootings happen at extremely rare rates among gun owners everywhere. This approach would be like comparing drunk driving fatalities in Los Angeles vs Venice, Italy. Edit: I was curious and just ran the numbers with the full OCED countries. The US had 0.136 rampage shootings per gun (compared to 0.120 rampage shootings per capita), and non-US countries had 0.177 rampage shootings per-gun (compared to 0.246 rampage shootings per capita). I used the author's numbers and the Wikipedia page data for guns/100 residents.
- habitue 11y agoThis is exactly the point. The variable in question is whether to try to reduce the gun-owning population to get shooting rates down. It sheds no light on that problem (and makes no sense) if you restrict the shootings to the gun owning pulations.
- girvo 11y ago> It's disingenuous to compare shootings purely by a per-capita basis. It should be per-capita among gun owners. First off, I don't live in the US and I don't have a horse in this race. You may have a point. However, wouldn't the fact that having a large number of gun owners directly correlating to mass-shooting fatalities still come down to the same conclusion: that guns should be regulated further? Or do you think that if the analysis was done it'd show something different to what the analysis in the original article shows?
- bmelton 11y ago> First off, I don't live in the US and I don't have a horse in this race. Not living in the US presumably subjects you to position bias. Those who live in countries where gun rights are strong tend to favor gun rights. Those who live in countries where gun control is strong tend to favor gun control. This is true of most things, as the moral compasses of most are drawn from what is currently normative to their existing environment. This is true of most places in which socio-political biases are codified into law, whether regarding religion, gay rights, whatever; Change in these areas tends to come slowly if at all. > guns should be regulated further Perhaps they should, perhaps they shouldn't. I have my bias, as I'm sure does everyone engaged in the discussion, but, at the end of the day, the document of the highest possible authority suggests that the citizenry should have access to guns, and the only way to overturn that is by ratifying that document. Thankfully, the document itself offers prescriptive measures for such ratification, but at the end of the day, without a strong enough amount of support throughout the nation and states for such a measure to pass. At present, such support does not exist, so our politicians play different games on what does or does not constitute "infringement". In the past, the argument was that it wasn't infringing if the person who wanted to exercise gun rights wasn't a member of a militia. We can prove historically and grammatically that this isn't true, but it took the Supreme Court's agreement for the legislature to accept it. Then, the argument was that sure, it's an individual right and not limited to those in the militia, but hey, the second amendment says you can keep and bear arms, but it doesn't say where, so instead, the government insists that the right is only applicable to within the home. Have as many guns as you like, and carry them anywhere you want, as long as it's inside your home. It took Chicago v. McDonald getting that one overturned in 2012 by the Supreme Court. So, legally speaking, we know that the right to keep and bear arms is an individual right, disconnected from membership in a militia, and it extends outside the home. To those who favor gun rights, the matter might settled, but to those who favor gun control, it's a challenge to come up with a new rule that doesn't directly contradict those recently affirmed rules by the Supreme Court. In D.C., the argument is currently that the right to keep and bear arms is only available to those with a heightened need... but what other right in our Constitution merits such a high bar to exercise? Would it be okay to restrict voting only to those harmed by the current administration? Would it be okay to limit speech only to those who can show that they have been victimized? Anyway, I'm obviously ranting, and there's certainly more of my bias in this post than I intended, so I should shut up. The point, that I'm sure I made poorly, is that the law here says that we can have firearms, and that not even the elected legislature has the power to overturn that without ratifying the Constitution... unless they can come up with something legally clever, or wait until there exists a more favorable court to their cause.
- ekianjo 11y agoExcellent article. I wonder what software was used for the computer simulation in the second part. Can one do that in R relatively easily ?
- emj 11y agoIf you use R it's easy, if you use python it's probably easier to that simulation there. It's more about knowing statistics, all of those conclusions in the article are not trivial to come to.
- CodeCube 11y agoHe mentions that it's a C#/WPF program that he wrote :) The article includes a link to download the code and play with it yourself: http://www.charlespetzold.com/blog/2015/07/RampageShootingStatistics.zip http://www.charlespetzold.com/blog/2015/07/RampageShootingSt...
- nabla9 11y agoIntresting note: Nordic countries (Finland, Norway) and Swizerland rank very high in gun ownership among OECD countries. http://www.nationmaster.com/country-info/stats/Crime/Gun-ownership/Guns-per-100-residents/2007 http://www.nationmaster.com/country-info/stats/Crime/Gun-own...
- anc84 11y agoThey are sparsely populated and wildlife is dangerous. Might simply be that and/or historical reasons.
- kwhitefoot 11y agoThat's the silliest thing I have seen for days. The wildlife in the Nordic area is very rarely dangerous. In the whole of Norway (60% more land area than the UK) there are a couple of dozen wolves and about 140 bears. The commonest large animal is elk and that is what the Norwegian hunting rifles are for. You are more likely to be bitten by an adder than attacked by a large mammal and even then fatalities are rare. As for the sparse population that is an example of averages being very misleading. Where there are any substantial numbers of people the population density is similar to the average for the UK while the mountains and high plains are almost not populated at all. I write as a long term resident of Norway.
- anc84 11y agoOops! At least I might have made you laugh. :)
- kwhitefoot 11y agoHave an upvote for having a sense of humour. :-)
- nabla9 11y ago>wildlife is dangerous LOL no. We have lots of guns because we hunt.
- cronjobber 11y agoThe reason we care about mass shootings is because people die. Petzold drops the one variable we care about and calls it de-obfuscation? Neat.
- OscarCunningham 11y agoIf you care about people dying then mass shootings aren't an important issue. (Compared to almost every other issue.)
- tljr 11y agoPerhaps looking to the stats, instead of the culture, is a symptom of the problem. No country left behind.
- Spooky23 11y agoThis brings up more questions than answers in my mind. Do we care about mass killings, or whatever is qualified as a "rampage shooting"? For example, Mexico has 1 "rampage shooting" in the data referenced in the article. Yet you have cartels killing dozens of people on a regular basis. The question in my mind is that if we don't have lots of "rampage shootings" in countries with lots of access to weapons, why does the US have so many? Why aren't developing countries with ubiquitous AK-47s experiencing this phenomenon?
- nraynaud 11y agocareful, these are OECD countries, so there are no third world countries. But your remark on Mexico rings true to me, maybe they are excluded because the victims are mostly not chosen at random.
- lagadu 11y agoWell I'd say it's a fair assumption to make that organized crime and "sporadic" shootings have wildly differing causes, unless you're willing to generalize to the point of saying "they're both caused by unspecified socio-cultural issues".
- Spooky23 11y agoPersonally, I'm more concerned about why folks in the US are going nuts in that way.
- VLM 11y agoAnd given the USA third world level (mental) health care system, and the general belief that most mass killers are pretty well insane, it is ridiculous to compare the USA with 1st world countries with 1st world (mental) health care systems.
- dsmithatx 11y agoAnd if you included all the killings in Chicago during the same period, it would probably make most of Mexico looks like Disney Land.
- sudioStudio64 11y agoPetzold is awesome. His blog has several articles he's written about his political views. I'm glad that someone with that kind of notoriety isn't afraid to write about politics.
- geggam 11y agoI would be interested in seeing the data correlating SSRI drugs to mass shootings statistically analysed so neatly
- innguest 11y agoI've been panning these comments with Ctrl+F for "SSRI" and you're the first one. You and I would be interested in seeing that data, and you and I will never see that data. ;) Also the media never ever mentions most of those shooter kids were on those hardcore FDA drugs. What's the point? We know the gun was responsible for the killings. /s
- hga 11y agoSeriously, we do believe these shooting are correlated with just plain mental illness. Which are largely "treated" with "those hardcore FDA drugs" (which SSRIs, due to the low side effect profile, really aren't), so therefore I'm not surprised there seems to be a correlation between the two. However, after a fair degree of study, and discussion with one of my psychiatrists a dozen or so year ago, I don't think there's causation, just correlation. Or at least he didn't believe the "antidepressants give you enough energy to be violent" thesis based on all three generations of them.
- innguest 11y agoWell, the same applies to the gun used (no causation, only correlation) and yet people and the media keep bringing guns up as if the correlation between 'using guns'<->'shooter kids' is stronger than 'using SSRIs'<->'shooter kids'. The psychiatrist you mentioned surely believes the same of guns, that guns can't possibly "give you enough energy to be violent". Because mostly they don't.
- cpr 11y agoIf you believe the self-provided warnings for these drugs, most or all of them warn about suicidal/violent mood side effects. One thing that people may not have heard about the Columbine shooters (because of the usual press corruption) is that they were sexually abused by the police, and were trying to get back at them.
- grkvlt 11y agoIsn't the fact that Norway appears near the top of this list only due to a single incident with a large number of victims, i.e. https://en.wikipedia.org/wiki/2011_Norway_attacks https://en.wikipedia.org/wiki/2011_Norway_attacks which skews the statistics. This is what he means when discussing small-N statistics being meaningless.
- jamesfe 11y agoYou know what Twain says - there are lies, damned lies, and statistics. (https://en.wikipedia.org/wiki/Lies,_damned_lies,_and_statistics https://en.wikipedia.org/wiki/Lies,_damned_lies,_and_statist...)
- phantarch 11y agoSherlock (or Doyle) says it best. "It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts." Petzold does a really good job of debunking the original claim that the US is not statistically significant when it comes to the number of mass shootings. However, all of the effort he goes through only points to one conclusion: the number of shootings we have in the US isn't statistically random. All this means is that there's something causing the rate of shootings to be higher here than is expected by random influences. It doesn't point to what that cause is. It's odd to see how statistics are abused by interest groups/media. Intuition is usually a pretty good yardstick for the validity of a statistic, insofar as knowing what kinds of conclusions should be able to be drawn from what kinds of data. If you've got a bunch of data about who likes what flavor of ice cream, it's not likely that data says anything about /why/ each person likes what they like. In the same way, it doesn't matter if you say that the US is normal when it comes to number of shootings or to say that it's abnormal as Petzold does, when you try to say /why/ this is the case, you better be drawing direct conclusions from your data.
- deleted 11y ago[deleted]
- avn2109 11y agoSpeaking of validity, it's not immediately obvious to me that each citizen of an OECD country constitutes a valid Bernoulli trial. Applying a uniform empirical prior of shooting rampage probability across the entire population strikes me as questionable. Presumably the results would be roughly convergent if he had done this with an inhomogeneous Poisson or something, but it seems a little handwavy to just fire off a binomial and call it good.
- adamtj 11y agoIntentionally or not, the author has cherry-picked the data in a way that completely undermines the article. The conclusion that "lives are at stake" is obviously true and supported by the data, but the implication that the US has too many guns is not. An analysis is only as accurate as the data. Here, the missing data makes it painfully obvious that, while we should whatever we can to reduce gun violence, we cannot morally accomplish it by disarming US citizens. If you merely look back to about 1939, you would find numbers for Poland alone that dwarf any statistics for the US, even ignoring differences in population! Poland isn't the only such example. Around that time, certain groups of people suffered from numerous horrific shootings, decimating their populations, despite those groups having been recently disarmed almost entirely. Of course, I'm being sarcastic. These people suffered at the hands of their own governments because they were disarmed, not despite it. There are some still alive who remember. An honest assesment of history, even very recent history, makes it clear that America's current level of gun violence is a mere rounding error next to the real threat: descent into tyranny. We're lucky that we live in such a relatively peaceful time, but let us not delude ourselves. No human will ever live without the threat of tyranny. No government of the people or by the people will ever, by it's own internal guidance, remain civilized indefinitely. We must never surrender the tools needed to provide the most drastic of course corrections for a government gone astray. We are fortunate that by keeping and maintaining arms, we make it more likely that we will never have to use them. Armed violence is always the absolute last resort, but if we give up our last resort, we give up all the other ones too. Speech, for example, is of little use against a tyrant with absolute power. But speech from the mouths of well-practiced riflemen, with their weapons close at hand? Those words cannot be safely ignored by anyone. It is for this reason that the right to keep and bear arms is not unique to just the United States. Rather, it is a fundamental and irrevokable human right. The Constitution of the United States does not and cannot grant this right -- though it does explicitly recognize it, lest we forget. Yes, gun violence is awful, and we should work hard to reduce it. But let us not forget that is is the price we pay for a civilized society, and it is a small price compared to the alternatives. I grow tired of articles that completely miss this point.
- smoyer 11y agoI'm to the right of president Obama, own guns (yes plural) and yet agree with him whole-heartedly. We, as a nation, need to figure out how to stop this violence. Please don't paint all conservatives with the radical right-wing brush. As an aside, I don't think Finland is celebrating in the streets with shouts of "we're number one".
- awptimus 11y agoThis article demonstrates the danger of thinking statistics is logic - you can only use statistics with the analytical framework firmly set up...not as a replacement. The United States is just that - United. States. 38 mass shootings, however defined, means there is /less than one per State/. Guess what? That makes Finland's two /much/ higher. That's...statistically significant! Explaining how completely incapable frequentist statistics are at describing anything at a low sample size doesn't mean that something succumbs to "random fluctuation." There is nothing random about a person deciding to take arms and shoot lots of people. Not only that, this data is based on a full population sample - it's not a survey of 5,000 people extrapolating to the whole population - it IS the full population. And he removed the idea that the original chart was designed show - lack of data that shows compelling evidence that more restrictive gun laws prevent either mass shooting incidents or mass shooting deaths. He should step away from the statistics - it's a loaded gun and he's not trained to use the weapon properly.