Guns and Crime: Correlation does not equal Causation

Many of the social sciences provide useful insights to problems, trends, provide metrics and measurable data for humanity as a group (social) or on an individual basis. Over the decades, they have gotten more sophisticated and advanced in study methodology, data collection techniques, and interpretive approaches. However, and despite all of these advancements, they are still circumspect to some, there have been charges of political bias, the narrowness in the backgrounds of the subjects in some social science research—think WEIRD—and problems with subjectivity and thus research bias being introduced into investigation methodology.  All valid points, to a point.  But the worst violators of using social science data to prove a point is not necessarily the researchers, but the people who popularize the research; media, politicians, ideologues, etc.

Case in point, the Washington Post’s own Wonk Blog. WB, in an attempt to discredit a gun rights advocate based study that indicates “More guns, less crime,” is now popularizing a recent study which purportedly “debunks” this study.

The notion stems from a paper published in 1997 by economists John Lott and David Mustard, who looked at county-level crime data from 1977 to 1992 and concluded that "allowing citizens to carry concealed weapons deters violent crimes and it appears to produce no increase in accidental deaths." Of course, the study of gun crime has advanced significantly since then (no thanks to Congress). Some researchers have gone so far as to call Lott and Mustard's original study "completely discredited." 

One of the major critiques of the study came from the National Research Council, which in 2004 extended the data through the year 2000 and ultimately concluded that "with the current evidence it is not possible to determine that there is a causal link between the passage of right-to-carry laws and crime rates." Or in other words, "More guns, less crime?  ¯\_ (ツ) _/¯ 

 Now, Stanford law professor John Donohue and his colleagues have added another full decade to the analysis, extending it through 2010, and have concluded that the opposite of Lott and Mustard's original conclusion is true: more guns equal more crime.  

"The totality of the evidence based on educated judgments about the best statistical models suggests that right-to-carry laws are associated with substantially higher rates" of aggravated assault, robbery, rape and murder, Donohue said in an interview with the Stanford Report. The evidence suggests that right-to-carry laws are associated with an 8 percent increase in the incidence of aggravated assault, according to Donohue. He says this number is likely a floor, and that some statistical methods show an increase of 33 percent in aggravated assaults involving a firearm after the passage of right-to-carry laws…

All I can say in response to “more guns equal more crime is “not really.”

You see, according to one study I found from the Congressional Research Service—Congress’s think tank-- on Gun Control Legislation (1993-2011) the impact of increased gun ownership apparently correlates to a drop in fire-arm related murders.

First let’s look at the number of guns in the United States, “The National Institute of Justice (NIJ) reported in a national survey that in 1994, 44 million people, approximately 35% of households, owned 192 million firearms, 65 million of which were handguns.” In 2009 the CRS estimates that the “estimated total number of firearms available to civilians in the United States had increased to approximately 310 million: 114 million handguns, 110 million rifles, and 86 million shotguns.”

Now that we have established that there was a rise in weapons availability the next step is to at least try and get some sort of estimate to the number of weapons owned in the United States within recent years. According to Pew Research, Social and Demographic Trends, “The 2007 Small Arms Survey, conducted by the Graduate Institute of International and Development Studies in Geneva (Completing the Count, 2007), estimated that 270 million firearms were owned by private citizens in the U.S. that year,¹³ or about 90 firearms per 100 people.”

So…from these two studies we can conclude that from 1994 until 2007 there was an increase in gun ownership of approximately 78 million weapons.  Moreover, since 2007 we can further reasonably deduce that gun ownership has steadily risen keeping pace with typical trends.

Now we will take a look at the amount of murder rates, firearm related murder rates, and non-firearm murder rates found in the CRS study.

From the early 90’s until 2011 there is a significant drop in total amount of overall murder rates. Specifically though in 1993 the firearm related murder rate was 6.6 per 100 thousand and in 2011 it measured 3.4 per 100 thousand. Subsequently as we see an increase in not only the availability of firearms but the ownership as well, there is a distinct and noticeable drop in the number of firearm related murder rates. But wait…it wasn’t just murder rates that were included in the Wonk Blog article, it was other additional crimes. Let’s take a look at the FBI’s Uniformed Crime Reporting Statistics and make a comparison.

As you can see since 1993 there have been dramatic reductions in the categories which are considered to fall under the description of violent crime.The very same categories indicated in the Wonk Blog article which are purportedly increasing. But there is a stark difference which must be mentioned and that is the study cited in the WB article has a very narrow field they are analyzing and that is the effect of right to carry--aka conceal carry--laws.  Conversely though the tone of the post doesn’t lend itself to that line of rhetoric, you are left with the impression by Wonk Blog that an increase in the number of guns directly correlates with an increase in violent crime. Take their comment in this paragraph which is an erroneousness observation. (Emphasis Mine)

Now, Stanford law professor John Donohue and his colleagues have added another full decade to the analysis, extending it through 2010, and have concluded that the opposite of Lott and Mustard's original conclusion is true: more guns equal more crime.

First off if correlation denotes causation which it doesn't always do, we have shown based on other sources that there is an ample pool of evidence contrary to the point Wonk Blog is attempting to make. Secondly if the Stanford study concentrates on Right to Carry laws, this is a completely different argument than stating that an increase in guns increases crime. You see “right to carry” does not increase the availability of weapons in purchasing or manufacturing terms, it is about your access to your personal weapons that are already in your possession. Even this is something I would remain skeptical of. 

The larger point here is not really my advocating for gun rights but how a journalistic grifter, or an equally gifted gun rights swindler for that matter, can use a case study to gin up the faithful and maybe sway fence sitters to their side. Being a charlatan can roll both ways when it comes to your personal agendas.

Addendum: Just for the record and integrity of this post I am a second amendment guy who supports gun rights advocacy. However, that support is limited by my candor.