Quote:

---

A few years back, a study was published by Kleck and Gertz which concluded that each year 2.5 million crimes were prevented by civilians (i.e., not police officers or security guards) with guns - by brandishing them, shooting them, or merely talking about them. This assertion is accepted and repeated by a large group of people.

The obvious flaws in the methodology of the study, as well as its factual conflict with reliable data, are interesting to dig into, but to me, a more fundamental question arises: Have people lost the ability to relate statistical assertions to their own very real lives so as to be able to detect even the most obvious BS?

The specific claim based on the study is this ("DGU" means "defensive gun use"):

Quote:

---

222 of the 4799 respondents reported having at least one DGU in their household in the past 5 years. After correcting for oversampling in some regions, this figure drops to 66 personal accounts of DGUs in the preceding year, indicating that 1.326 percent of adults nationwide had experienced at least one DGU. When multiplied by 1.478, the average number of DGUs reported per DGU claimant for the preceding year, and by the total adult population, an estimate of 2.55 million DGUs per year was arrived at.

---

Okay, let's just mull that over for a minute. 1.3% of all American adults prevented at least one crime - last year - by brandishing, shooting, or referring to a gun. Not only that, but it happens year in and year out. And it's not the same 1.3% every year - while there's some overlap, the study results actually suggest that for the most part it's a new group doin' it each and every year (222/4799 yields 4.6% over five years, or a new .9% of the population engaging in DGU's each year).

So, my having been an adult for about forty years, I should personally know a lot of people this has happened to. 40 X .9 = 36%! Of course the population has turned over during that time period with old people dying and new people achieving adulthood, so if it was done just once per lifetime by each defender it'd be closer to 18%. If we pump up the "repeat defender" rate by assuming that there are repeaters from one 5 year time span to another so we don't have to assume that 18% of all Americans engaged in DGU over that period of time we're still left with a substantial fraction of the population. I mean, during that time there's probably a hundred people I've known really well - well enough so that if they had prevented an actual crime (and used a gun to do so) I'm confident that I'd know about it. But I don't. I actually don't know a single one. I do know that people do prevent crimes, both with and without guns, and I've personally participated in crime prevention a couple of times. (I've lived in some fairly high-crime areas.) But actual "crime prevented by gun-totin' civilian"? Absolutely zero first hand experience, zero reliable second hand experience.

So even without digging into the details of the study, it's not really too hard for me to figure that it really is a remarkable claim, which is inconsistent with my actual real life experience. In short, my BS meter isn't just twitching - it's hit the peg. And frankly - that was before I ran the numbers above - I just did that as a reality check. They had me at "2.5 million times a year."

So why do people just accept a claim like this? If people were actually preventing crime all the time - 120,000 time per month - we'd actually know about lots and lots of actual such events, involving people we actually know. But we don't. At best most of us have a "friend of a friend" that we've heard about, or read a story in the newspaper (since such events would typically be dramatic and newsworthy) But we don't actually have anywhere near the reliable personal information we should have if this claim were true.

So why do people believe stuff which doesn't even fit with their own very real lives? http://talk.collegeconfidential.com/parent-cafe/430919-why-do-some-peo
ple-believe-2-5-million-crimes-prevented-guns.html

---

Quote:

---

...a study published in 1995 arguing that Americans use guns in self-defense some 2.5 million times a year, or once every 13 seconds. A Google search finds more than 1 million citations of this study posted online.

1) Even if you think the 2.5 million statistic was correct at the time it was computed, it must be obsolete today. The 1995 study was based upon data collected when crime rates were vastly higher than they are today. Some of the data was collected in 1981, near the very peak of the post-Vietnam War crime wave. It's just incredible on its face that defensive gun use would remain fixed at one level even as criminal attempts tumbled by one-third to one-half.

2) When we hear the phrase "defensive gun use," we're inclined to imagine a gun owner producing a weapon to defend himself or herself against bodily threat. The authors of the 1995 study aggregated 13 prior polls of gun users, most of which did not define what was meant by "use." As the authors of the 1995 aggregation study themselves ruefully acknowledged: "The lack of such detail raises the possibility that the guns were not actually 'used' in any meaningful way. Instead, (respondents) might be remembering occasions on which they merely carried a gun for protection 'just in case' or investigated a suspicious noise in their backyard, only to find nothing." In other words, even if the figure of 2.5 million defensive gun uses had been correct at some point back in the early 1990s or early 1980s, the vast majority of those "uses" may be householders picking up a shotgun before checking out the noises in the garage made by raccoons rooting through the trash.

3) The figure of 2.5 million defensive gun uses is supposed to represent the number of such uses per year. Yet none of the studies aggregated in the 1995 paper measured annual use. Most asked some version of the question, "Have you ever?" Two asked instead, "Have you within the past five years?" The authors of the 1995 study took those latter two surveys, multiplied the rate in the survey by the number of U.S. households, then divided by five to produce an annual figure.

It's not very likely that many respondents thought, "Today it's August 1990. I do remember scaring off a prowler in June 1984. But that was more than five years ago, so the answer to the question is 'No.' Not within the past five years."
More likely they thought, "I'll never forget the night I warned off a prowler with my shotgun. That was scary. Man, I'm glad I had my gun ready. When was that anyway? Three years ago? Four? I don't remember exactly, but the answer to the question is 'Yes.' "

4) Meanwhile, over in the world of hard numbers, the FBI counted an average of 213 justified firearm homicides per year over the period 2005-2010. If the figure of 2.5 million defensive gun uses were any way close to accurate, it would imply that brandishing a gun in self-defense led to a fatality only 0.00852% of the time. That seems almost miraculously low.

5) Underneath all these statistical problems is a larger conceptual problem. When we hear "defensive gun use," we're invited to think of a law-abiding citizen confronting a criminal aggressor. Yet crime does not always present itself so neatly. The vast majority of homicides take place between intimates, not strangers. Assaults, too, are often an acquaintance crime.

Perhaps when we hear "defensive gun use," we should not imagine a householder confronting a prowler. Perhaps we should think of two acquaintances, both with some criminal history, getting into a drunken fight, both producing guns, one ending up dead or wounded, the other ending up as a "DGU" statistic -- but both of them entangled in a scenario that would have produced only injuries if neither had carried a gun.

To be clear: I'm not disputing that guns sometimes save lives. I'm questioning the claim that widespread gun ownership makes America a safer place. The research supporting that claim is pretty weak -- and is contradicted above all by the plain fact that most other advanced countries have many fewer guns and also many fewer crimes and criminals.

But most of the time, gun owners are frightening themselves irrationally. They have conjured in their own imaginations a much more terrifying environment than genuinely exists -- and they are living a fantasy about the security their guns will bestow. And to the extent that they are right -- to the extent that the American environment is indeed more dangerous than the Australian or Canadian or German or French environment -- the dangers gun owners face are traceable to the prevalence of the very guns from which they so tragically mistakenly expect to gain safety.Excerpts from http://www.cnn.com/2012/07/30/opinion/frum-guns-safer/index.html

---