David R. Henderson  

Brian Doherty on Guns, Crime, and Gun Laws

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This morning when I was reading the blogs, the title of Brian Doherty's article caught my eye: "You Know Less Than You Think About Guns." Really? Well, it turns out that, if he was addressing me, he was right. His article is a very careful look at the data on guns, crime, violence, and gun laws. It took me about 20 minutes to read and absorb it.

I recommend the whole thing--it's long, but worth reading.

Some nuggets:

Guns Up, Homicide Rate Down:

This simple point--that America is awash with more guns than ever before, yet we are killing each other with guns at a far lower rate than when we had far fewer guns--undermines the narrative that there is a straightforward, causal relationship between increased gun prevalence and gun homicide. Even if you fall back on the conclusion that it's just a small number of owners stockpiling more and more guns, it's hard to escape noticing that even these hoarders seem to be harming fewer and fewer people with their weapons, casting doubt on the proposition that gun ownership is a political crisis demanding action.

In the face of these trend lines--way more guns, way fewer gun murders--how can politicians such as Obama and Hillary Clinton so successfully capitalize on the panic that follows each high profile shooting? Partly because Americans haven't caught on to the crime drop. A 2013 Pew Research Poll found 56 percent of respondents thought that gun crime had gone up over the past 20 years, and only 12 percent were aware it had declined.


Suicides versus Homicides:
Critics quickly noted that the [National] Journal's Libby Isenstein had included suicides among "gun-related deaths" and suicide-irrelevant policies such as stand-your-ground laws among its tally of "gun laws." That meant that high-suicide, low-homicide states such as Wyoming, Alaska, and Idaho were taken to task for their liberal carry-permit policies. Worse, several of the states with what the Brady Campaign to Prevent Gun Violence considers terribly lax gun laws were dropped from Isenstein's data set because their murder rates were too low!

The Importance of Outliers in Affecting the Results
Among other anomalies in Fleegler's research, Hinderaker pointed out that it didn't include Washington, D.C., with its strict gun laws and frequent homicides. If just one weak-gun-law state, Louisiana, were taken out of the equation, "the remaining nine lowest-regulation states have an average gun homicide rate of 2.8 per 100,000, which is 12.5% less than the average of the ten states with the strictest gun control laws," he found.

Having a Gun in the Home: Better Not to Be a Renter
The idea that keeping a gun in the home puts owners and their families at elevated risk first rose to prominence in a 1993 New England Journal of Medicine article by Arthur Kellermann and his colleagues. "Although firearms are often kept in homes for personal protection," they concluded, "this study shows that the practice is counterproductive."

The study has many flaws. In addition to the predictable failure to establish causality, there's a more glaring irregularity: Slightly less than half of the murders Kellermann studied were actually committed with a gun (substantially less than the national average in 1993 of around 71 percent). And even in those cases he failed to establish that the gun owners were killed with their own guns. If even a small percentage of them weren't, given that more than half of the murders were not committed with guns, the causal relevance of the harmed being gun owners is far less clear. (The study found that even more dangerous risks than having a gun at home included living alone, using drugs, or being a renter.)


If You Don't Run, Use a Gun
In the October 2015 special issue on "gun violence prevention," Preventive Medicine featured the latest and most thorough attempt to treat the NCVS as the gold standard for measuring defensive gun usage. The study, by Harvard's Hemenway and Sara J. Solnick of the University of Vermont, broke down the characteristics of the small number of DGUs [Defensive Gun Uses] recorded by the NCVS [National Crime Victimization Survey] from 2007 to 2011. The authors found, among other things, that "Of the 127 incidents in which victims used a gun in self-defense, they were injured after they used a gun in 4.1% of the incidents. Running away and calling the police were associated with a reduced likelihood of injury after taking action; self-defense gun use was not." That sounds not so great, but Hemenway went on to explain that "attacking or threatening the perpetrator with a gun had no significant effect on the likelihood of the victim being injured after taking self-protective action," since slightly more people who tried non-firearm means of defending themselves were injured. Thus, for those who place value on self-defense and resistance over running, the use of a weapon doesn't seem too bad comparatively; Hemenway found that 55.9 percent of victims who took any kind of protective action lost property, but only 38.5 percent of people who used a gun in self-defense did.

John Lott's Work
The range of contentious issues involved in Lott's techniques were summed up pretty thoroughly in a sympathetic but critical review of the third** edition in Regulation. The economist Stan Liebowitz of the University of Texas at Dallas wrote: "Should county level data or state level data be used? Should all counties (or states) be given equal weight? What control variables should be included in the regression? What violent crime categories should be used? How should counties that have zero crimes in a category, such as murder, be treated? How much time after passage of a law is enough to determine the effect of RTC laws? What is the appropriate time period for the analysis?"

Lott tried to demonstrate that on the county level, violent crime trends showed signs of improvement in counties that had or passed RTC laws compared to counties that had not, among other things checking both mean crime rates and the slope of crime rates before and after RTC passage. He attempted to control for many handfuls of other variables that might affect crime rates--indeed, some researchers accused him of accounting for too many variables, while others slammed him for failing to account for other factors, like conviction rates or length of prison sentences.

Trying to prove Lott wrong quickly became a cottage industry for others interested in the nexus of guns and public safety. The back-and-forths were so extensive that the latest edition of Lott's book is nearly twice as long, with his reactions to his critics.


Comparing Connecticut and Rhode Island After Connecticut's Gun Law
Rhode Island's murder rate went up unusually after 1997 (the researchers don't speculate on why that might have been), thus creating some "extra" murders (presuming that choices to murder in Rhode Island would have for some reason created a proportional number of choices to murder in Connecticut) that we can credit Connecticut with having evaded thanks to the more stringent gun law.

But what happens when you extend the analytic period beyond the arbitrary cutoff date of 2005? From 2005 to 2012, Connecticut's gun murders per 100,000 people increased 66 percent, from 2.05 to 3.41, while Rhode Island's went down 20 percent, from 1.83 to 1.45. It seems quite premature to take Webster and his team's counterfactual guess about expected murder rates over one 10-year period as establishing any reliable causal knowledge about the effects of tougher gun purchasing laws. Yet that study was used to help buttress a proposed federal law the week it went public, trying to pressure other states into following Connecticut's lead on background checks and permits, given what we now "know" about how life-saving that move had been.


Cost-Benefit Analysis Leaving Out a Key Set of Benefits
As Harvard's [David] Hemenway explained to me, the confidence intervals of the social sciences in colloquial terms demand a belief that the chances are 19 to 1, or at worst 10 to 1, for you being right about your conclusion before you accept it as provisionally verified. Hemenway also believes, given the good he thinks can come from legal interventions about guns, that we don't need to be that certain we are right for policy work.

But that's easier to accept if you don't value any particular benefits to relatively unrestricted private gun ownership--scientific, constitutional, or just personal. Some researchers, particularly in the public health field, act as if there were no values to balance on the other side of the policy goal of making it harder for people to get guns.


The Bottom Line
Whether you consider the associations and causations supposedly demonstrated by gun-related social sciences to be proven beyond whatever level of doubt you see as appropriate, applying those stipulated facts to policy questions can never itself be a purely mathematical or scientific process. It's politics all the way down, and that politics is less informed by rigorous and certain knowledge than President Obama thinks.


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COMMENTS (12 to date)
ThomasH writes:

"proposition that gun ownership is a political crisis demanding action."

I do not think this is a crisis, just good preventive public health, like vaccinations.

It seems that the reasonable middle ground that balances costs and benefits would be to license guns to those with a good reason to need them, and demonstrated ability to use the type of weapon purchased for the intended use. Those that want to use a gun to protect the public in a shooter situation, for example would show that they can respond appropriately in such a situation. As we've see in police shootings, using a gun in an emergency situation is not easy and requires considerable training. But guns should not be banned. People have a Constitutional right to own a gun for self protection.

Tangentially related: ...
Let A = {x: x is a US citizen who may legally purchase firearms}.
Let B = {x: x is a US citizen who may legally vote}.
These sets are nearly co-extensive.
If the procedure by which dealers establish a prospective buyer's membership in A is so easy as NOT to interfere with the right to keep and bear arms, how can voter ID be difficult?
Do we have the makings of a deal?

Harold Cockerill writes:

In all of the discussions of how to address "gun violence" something that is almost invisible is how race is a major factor in the composition of gun death statistics. Blacks die at the hands of other blacks and commit a disproportionate percentage of murders given their population. The majority of white deaths by gun are suicides (per CDC figures).

How do black murderers procure the guns they use? If it's not in the flow that's controlled by background checks then why think expanding those checks will have an effect on gun violence? Laws making it more difficult for honest people to buy guns most likely will have little effect on crime statistics. Does the president realize this? If he does then one might conclude the push for more gun control is not about crime.

Nathan W writes:

The best way to reduce gun violence is to legalize drugs and restrict access. This will end the turf wars and gang violence responsible for a lot of inner city crime.

Hasdrubal writes:
Having a Gun in the Home: Better Not to Be a Renter

The results of research quoted in this section of the article really seems to be results of the "garden of forking paths," as Andrew Gelman puts it. Or "green jelly beans cause cancer!" as XKCD does. It sounds like an awful lot of specifications were tried, on a lot of data sets, and the statistically significant results were reported.

Some of the results make sense (you're more likely to defend yourself successfully if you use a gun.) And I can certainly come up with just so stories to explain others (apartments are a proxy for urban, which has a higher crime rate.) But those are all ex post explanations, and I seriously doubt those statistical findings take the multiple interactions between the different tests into account.

The takeaway for me is: We've done a lot of research on gun violence and we don't even have an agreement on what the sign of the relationship between legal gun ownership and crime is. To me, that means the effect size is small, regardless of the relationship. There's no low hanging fruit, "common sense changes" aren't going to make a noticeable impact.

But yeah, crime is down. A lot. Including gun crimes and murder. Another thing, while the US murder rate is higher than the OECD, our overall crime rate, including violent crimes, is actually lower than a lot of other countries. Including developed OECD countries.

Tyler Wells writes:

I love it how easy it is to ignore the experiences of the other developed countries when it suites the purpose of the argument. I'm all for liberty but not at the expense of honesty and common sense.

run75441 aka Bill H writes:

Interesting commentary.

Black killing of blacks is in the ninety percentile and white killing of whites is in the eighty percentile with bullet-spewing-weapons. FBI stats as explained here: https://www.fbi.gov/about-us/cjis/ucr/crime-in-the-u.s/2013/crime-in-the-u.s.-2013/offenses-known-to-law-enforcement/expanded-homicide/expanded_homicide_data_table_6_murder_race_and_sex_of_vicitm_by_race_and_sex_of_offender_2013.xls and talked more about here: http://www.vox.com/2015/10/3/9444417/gun-violence-united-states-america

When the US is compared to other and SIMILAR countries such as in Europe, we are head and shoulders above those countries in homicides whether most of them are suicides or not.

You guys(?) are dancing around this. Yes gun violence is down; but as a supposedly the pinnacle nation of "civilization," the US still leads the pack in deaths as caused by bullet-spewing-weapons.

Now that the crowd has discussed African American violence, what is up next Muslims???

pyroseed13 writes:

The Doherty post is a very nice summary, but respectfully, that gun rights advocates only have two researchers to cite on these issues over and over, Kleck and Lott, weakens their case. Lott's results have been tirelessly debunked and don't hold up under empirical scrutiny. Of course, much of the same can be said for the research published by gun control advocates such as Hemingway. These studies are so sensitive to model specifications that just changing a few parameters or altering the sample can produce dramatically different results. As for Kleck, the results just seem implausible. Even according to his own survey, half of DGUs were reported to police, yet where are the police reports showing that there are a least half of his estimated 2.5 million DGUs? I'm not sympathetic to gun control, but I am sympathetic to good research, and we just have not seen much of it on this issue.

ColoComment writes:

I just read that article this morning, and was impressed with the balance of it.

However, it does seem to me that if you're seeking to limit, restrict and infringe on a Constitutional right*, you should have not only a compelling government/public interest, but also rock-solid evidence that the infringement will satisfy that interest. That evidence just isn't there.

* and do let's recall that the Founders thought this right important enough to toss into the Bill of Rights in second place, right after the four freedoms, and before the quartering of military in their very own houses.

As an aside: I wonder if there was a coherence to that: that the 2nd A would tend to guarantee that the 3rd A would not happen?

ColoComment writes:

Charles Cooke takes on "Heller" disputants.

http://www.nationalreview.com/article/429402/second-amendment-individual-right-guns

Bill Conerly writes:

This article can be taken much more broadly than about gun control. If you dig into minimum wage, gender gap, or many other topics, you find generalizations that fall apart under careful analysis. It's really, really hard to reach conclusions based on empirical analysis.

Every study reported in the press, including biology, sociology, and other data-intensive fields, should be taken with a grain of salt.

Daublin writes:

@ThomasH, how would that differ from the status quo? Guns are already controlled.

Perhaps you mean that guns should be *more* controlled, but how do you picture that working, exactly? Guns are small physical objects that are easily handed from one person to the next. It's not like controlling uranium, where there are few enough stashes existing in the world that each staff can have its own dedicaded team of officials from multiple governments to monitor their proper use.

@Hasdrubal, yours is the voice of reason. If you try to solve a small problem, you can't possibly reduce it very much, because it's already small.

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