Wednesday, January 16, 2013

From a professional statistician

The homicide rate in 2011 was the lowest on record since 1960.

The lowest number of homicides by firearm was in 2011.

Firearm Homicides Are Dropping.  Assault Weapons Ban Not Correlated With Decrease In Homicides. No Need For New Restrictions.

by William Briggs
January 16, 2012

I rarely ask this, but please link, forward, email, and favorite this post as widely as possible. See below for copying permission.

Murder in the United States1 is illegal, and has been for over two hundred years. Strong penalties, up to and including the penalty of death, are incurred by those who commit this heinous crime.

Yet, strangely, despite murder’s high illegality, there were in 2011 over 12,000 of them committed! The largest number of murders were in 1991, with nearly 25,000 of these frowned-upon unlawful incidents.

It is difficult to imagine a penalty more severe than death, so it remains a curiosity that so many murderers are found when such strong laws are in place. Perhaps this scourge can be eliminated by even tougher laws?, say death by torture? Or maybe by creating Executive Orders bypassing the hindrance of Congress and Constitutional safeguards? We must protect the children!

But never mind. Let’s instead look at the number of murders and what devices were used in their commission.

This (Fig. 1), according to the FBI2 and the United States Census, is the per-capita murder and non-negligent manslaughter (hereafter, in a slight abuse of notation, just called “homicide”) percentage from 1960 to 2011 (data for 2012 were not yet available). Overlaid are the same percentages for just those bodies accumulated from deaths by any type of firearm.

Figure 1

Figure 1

The first notable is that the two rates track closely, so that whatever is driving changes in the one is likely (but not certainly) driving changes in the other. The second remarkable feature is the abrupt increase in the turbulent 1960s, and the subsequent decline as the people responsible for these cultural excesses began to enter their 50s and 60s, and even to die off in the 2000s and 2010s. The percent in 2011 was the lowest on record.

I want to repeat that: The homicide rate in 2011 was the lowest on record since 1960.

And that’s true for all homicides committed with firearms of any type; that is, the lowest number of homicides by firearm was in 2011—although I only could find data from 1975-2011.

Let’s repeat that, too: the lowest number of homicides by firearm was in 2011.

Is your first reaction panic? Deep concern? Do you feel in your gut the need to do something? Then I suggest switching to a decaffeinated brand.

Now let’s look at the shaded region on the plot, which is the time the Orwellian-named “Public Safety and Recreational Firearms Use Protection Act”, i.e. “‘Assault’3 Weapons Ban”, was in force, from 13 September 1994 until the same date in 2004. There does not appear to be much correlation between this ban and the homicide rate: homicides both decrease and increase during the time which it was in force.

If you think there might be a correlation, then look at this plot (Fig. 2), which is the homicide rate for handguns, separated from other firearms4, knifes, blunt objects, and other instruments, which is a catchall including poisonings, strangulations, drownings, and similar forms of mayhem.

Figure 2

Figure 2

Each of these series exhibit the same pattern as the overall homicide rate. You may say the “assault” weapons ban lowered the rate of homicides committed with firearms, but then you have to explain why poisonings, strangulations and the like similarly decreased. It is of course possible that would-be murderers, feeling deprived of their loss of frightening-looking “assault” weapons were so forlorn that they lost the heart to add cyanide in their enemies’ tea, but it’s more likely that whatever was responsible for the general decrease in bloodlust caused both the decrease in firearm and non-firearm homicides.

Another possibility is that the number of shootings and other forms of violence remained constant, or even increased in recent years, but that people once wounded, because of improvements in medical science, are not dying at higher rates. This necessarily would decrease the homicide rate for the simple reason that if a person survives a shooting, he cannot be considered murdered. But this explanation is not plausible given that violent crimes (which includes attempted murder) are also on the wane, as shown here (Fig. 3).

Figure 3

Figure 3

There is some evidence that medical science might be the cause of some of the decreased homicide rate from this next plot (Fig. 4), which shows the percentage of homicides of all violent crimes: from a high of 3% to now around 1%. But since violent crimes as a whole are dropping, it is even more plausible that people are just becoming less bloody minded; i.e., less in the need of government control and regulation.

Figure 4

Figure 4

What should be particularly clear from the Figure 2 are two things: (1) homicides by any type are decreasing, and (2) handguns, and not “assault” rifles or indeed any other type of firearm, are always the most-used weapon. This plot (Fig. 5) emphasizes the significant role of handguns

Figure 5

Figure 5

This is a conditional plot, showing the percent handguns and other firearms are used in homicides. Notice that the percent of homicides committed with non-handguns actually increased during the life of the “assault” weapons ban. Handguns hover around 50%, a little more than 3 times as prevalent as non-handguns. If there are calls to ban anything, one would therefore guess it would be handguns which are demonized, not rifles and shotguns. Alas, the mind of the politician is a difficult thing to grasp.

Now let’s look at the same plot again (Fig. 6), this time including all types of killing methods:

Figure 6

Figure 6

The two rivals, equaling or exceeding in lethal importance to “assault” weapons (and other non-handguns), are knives and other types of weapons, such as poisons, strangulations, and fire. Yet we never hear even rumors of politicians wishing to ban fire. Though we do hear, all too often, of impaired officials banning children for pointing their fingers.

Summary: to use a phrase coined by Father Z, the “biological solution” appears to be lowering homicide rates quite well, with no government intervention required (or desired).

Now for the punchline. None of the statistics presented here are new or unknown. They are available to every politician, and indeed every lawmaker with the word “ban” on his lips knows them well (otherwise they are incompetent). Each of these people, like you now, knows that limiting “assault” weapons will do little to change the homicide rate. Yet still they want to ban. Why?

Could it be—this is reasonable to ask—that they have a different agenda in mind? Did we not hear many elected officials (from both major parties) tell us that guns are “only for hunting”, and did not some call for the confiscation of all guns? I suspect that this is the sole reason for the current flurry, the drive to “never let a crisis go to waste”: to strip citizens of their guns. Not all at once, for that would lead to rebellion, but slowly, incrementally, a death through many small paper(work)cuts.

Addendum The number of mass public shooting incidents per decade have also been decreasing and are uncorrelated with gun ownership. Full details about Fig. 7 are here.

Figure 7

Figure 7

Update Comparisons of the enormous, socially and racially heterogeneous United States with small, relatively more homogeneous European countries are not persuasive. “Denmark has lower gun violence!” somebody will proudly say, forgetting that Denmark on crowded day has only three-fourths the population of New York City.

Update As predicted. “Our children’s safety.

Update On one of the pages that linked to this story (thank you), one person called me an “economist.” Grr. His contention was that I did not focus on “assault” weapons, but only “other firearms.” This individual forgot that “assault” weapons are a subset of “other firearms”, and so are handled in that manner. Murders with them are limited to the number of murders of “other firearms.” And then—and this it the point—the FBI does not have readily available individual statistics separating “assault” weapons. Which makes me wonder how this individual (or anybody) could be so confident that “assault” weapons were such a scourge.

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Notes:

1Murder has not always been illegal everywhere. For example, citizens who were deemed “counter-revolutionary” or “anti-government” were routinely slaughtered, quite legally, in countries with international and national socialist governments. These countries, perhaps entirely coincidentally, banned their citizens from owning most or all firearms. I define murder as unlawful under the law given to us by a Higher Authority.

2Here is the data, which was compiled from several government sources, such as here, here, here, here, and here. Multiply Population by 1000. The data is not 100% certain. I found, on the FBI’s own site, different numbers for homicides for the same years. The discrepancies were never more than a couple of hundred coffins, but this still indicates imperfection. And that means we should lessen the certainty we have in any conclusions we draw from this data.5 If anybody out there can find mistakes or additions to this spreadsheet, please do so by amending it and emailing it back to me at matt@wmbriggs.com. I will then (at some point) redo and create a new post.

The FBI says murder and non-negligent manslaughter are:

the willful (nonnegligent) killing of one human being by another. Deaths caused by negligence, attempts to kill, assaults to kill, suicides, and accidental deaths are excluded. The program classifies justifiable homicides separately…Deaths of persons due to their own negligence, accidental deaths not resulting from gross negligence, and traffic fatalities are not included…

The murders on “September 11th” are not included in these charts, but the Oklahoma City bombings are.

3It has been said that an “assault” weapon is that which looks frightening to a lawmaker. Given the increase in non-manly politicians—by which I mean folks unable to appreciate a John Wayne movie—more and more weapons will be so categorized.

4A 2009 Attorney General report from California showed that fully automatic weapons, like “machine” guns, are used in 1% of crimes in that state. How could this be? Aren’t these guns illegal everywhere? If it’s one thing you can count on, it’s that a criminal has no respect for the law.

5Footnote to the footnote! Firearm laws vary across state and, within states, across time and across regions. The federal government, jealous of the power of the states, enacts its own laws, which also change through time and by region. The laws everywhere vary in strength, too. Further, citizens move from one state to another, or they move within a state to areas which have different laws. The compositions of the folks living in these great United States has also changed radically since 1960. Therefore, any statistical analysis—usually some high falutin regression model—which purports to have figured out the true influence of firearms regulations will be full of—what our esteemed Veep Joe “Wakka Wakka” Biden called—malarkey.

One thing we can say with certainty: threats to increase restrictions on firearms increase the sales of firearms: heres one example of many.

William M. Briggs, the “Statistician to the Stars!” is, and has been for many years, a proud NRA member. He received no consideration of any kind from anybody for this post.

Permission is granted to copy and reprint this post, under the proviso that my name and a link to my site accompanies it.

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