Explore The NRA Universe Of Websites

APPEARS IN News

Questionable Metrics in New Study

Friday, March 29, 2019

Questionable Metrics in New Study

A Columbia University doctoral student in epidemiology and professors from the NYU School of Public Health, the BU School of Public Health, and the Penn School of Medicine published a study last week in The BMJ (formerly known as the British Medical Journal) that purports to have found that “states with more permissive gun laws and greater gun ownership had higher rates of mass shootings, and a growing divide appears to be emerging between restrictive and permissive states.”

Studies like this are often, unfortunately, publicized without much critical thought. An article in The Houston Chronicle claims that this study “pushes back against” the argument that one’s personal safety is increased by owning a firearm. This study does no such thing, but why let a detail like this derail some anti-gun media bias at its worst.

The study’s researchers used The Traveler’s Guide to the Firearm Laws of the Fifty States to give each state an annual rating between 0 (completely restrictive) and 100 (completely permissive). This is a central component of their analysis but the Traveler’s Guide was not designed for this use. The ratings in the Guide are arbitrary and seemingly give each law the same weight when some laws are more onerous to gun owners than others. Even Daniel Webster, the Bloomberg Professor of American Health at the Bloomberg School of Public Health and the Director of the Johns Hopkins Center for Gun Policy and Research, raised this issue with Vox, telling them that indices like this make “it hard to draw concrete policy lessons from findings attached to such indices.” The Vox article spreads more inaccuracies about gun laws and related research than we can address here, but including even a bit of criticism is a welcome change from how other media outlets regurgitate the flawed findings of anti-gun researchers.

This is not to disparage The Traveler’s Guide. It is both interesting and useful but it was designed as a quick reference for traveling gun owners. Using it in an attempt to quantify the differences in gun laws between states is ill-conceived at best. The study’s researchers also failed to reach out to the author of the Guide, so it’s clear they also had no additional insight into the rankings.

We couldn’t find an explanation for the scoring in the Guide, but more recent versions have detailed the reasons for a change to a state’s score for a given year. In 2018, Arizona’s score was stable from the prior year and this was the explanation: “wide open desert & Constitutional carry make it one of our best.” Arkansas saw a score increase of 3 points for enacting an enhanced concealed carry permit, while Iowa saw stand your ground, a preemption upgrade, and State Capitol carry enacted and only gained five points. Even if there were a formula behind the score, it would still be arbitrary. There are also some odd categorizations in the Guide. For example, California is listed in the 2010 edition as having “unrestricted, no permit or license required” to own a firearm but the state began requiring residents to obtain a handgun safety certificate before they could acquire a handgun in 2001.

The full data set was not available at the time of this article, but the charts included in the study show that Massachusetts, Connecticut, Illinois, and Maryland are all more restrictive than California during the study’s time period (1998-2015). Does that sound right to you? It doesn’t sound right to us.

But – again – the scores are based on a guide written for travelers and there is no described system for assigning the scores. It is arbitrary and for informational purposes only. It was not designed for use in an analytical model.

The annual score is not the only issue with this Columbia study. The researchers used a proxy for gun ownership rate that is the ratio of suicides involving firearms to total suicides in a state. This proxy is widely accepted but is not typically used as an independent variable, the central variable of interest in an analysis. Some reasonable control variables were included, but violent crime rate and age cohorts were not. There was no mechanism to control for enforcement of laws, which is important when comparing a range of policies across states. The outcome variable presents the next considerable issue with this analysis. The outcome variable is the number of mass shootings per million people in a state, drawn from the FBI’s Uniform Crime Report Supplementary Homicide Reports, which does not include all homicides from all states and do not include the state of Florida at all. Excluding one of the most populous states is odd.

Let’s look at the data the researchers did use. They “found” 344 mass shootings from 1998 to 2015. The Mother Jones website lists 51 for the same time period. Mother Jones excludes incidents that occur as part of another crime (like a robbery, a home invasion, or gang activity) and focused on incidents in public places. The Columbia study apparently used a broader definition which yields a considerably higher number. It is important to consider the definition used. The researchers defined a mass shooting as “one event in which four or more individuals were killed by a perpetrator using a firearm and the perpetrator themselves did not count toward the total number of victims.” This sounds reasonable, but it includes targeted attacks, domestic incidents, and other criminal activity. The phrase “mass shooting” invokes the sort of random, public rampage as defined by Mother Jones.

Vermont had the highest rate of mass shooting deaths in this time period, at just below 0.3 per million people. The Gun Violence Archive also uses a broader definition of mass shootings and reports a single incident in Vermont in the time period: a horrific event in which a woman killed three relatives and a social worker after losing custody of her child. While this is undeniably a terrible crime, it’s not typical of the type of crime most Americans think about when discussing mass shootings. This crime also shows how even a single incident in a low population state can substantially distort a dataset when dealing with rare events. 

Readers may notice that the rate of mass shootings is presented in terms of “per million people” instead of the customary “per 100,000 people.” This is because mass shootings are fortunately rare. Public mass shootings, the sort of incidents that the public consciousness associates with the term, are even more rare.

That is part of the reason why mass shootings are so difficult to study.

These events are even harder to study when the variables used in the analysis do not measure what they are purported to measure.

 

 

IN THIS ARTICLE
Research Bias
TRENDING NOW
U.S. Senate Adds Pro-Gun Tax Relief Language Back into Reconciliation Bill

News  

Saturday, June 28, 2025

U.S. Senate Adds Pro-Gun Tax Relief Language Back into Reconciliation Bill

Overnight, the U.S. Senate added pro-gun tax relief language back into the Reconciliation bill after the Senate Parliamentarian struck out an earlier provision.  While this new provision is not as expansive as the language we advocated for which ...

U.S. Senate Forced to Remove Pro-Gun Language from Reconciliation Bill

News  

Friday, June 27, 2025

U.S. Senate Forced to Remove Pro-Gun Language from Reconciliation Bill

Today, the U.S. Senate was forced to remove the pro-gun language that had been previously included in the Reconciliation Bill currently making its way through the chamber. We explained in a previous article that this language would, ...

U.S. House Passes Reconciliation Bill, Removing Suppressors from the National Firearms Act

News  

Second Amendment  

Thursday, May 22, 2025

U.S. House Passes Reconciliation Bill, Removing Suppressors from the National Firearms Act

Earlier today, the U.S. House of Representatives passed H.R.1 the One Big Beautiful Bill Act, which included Section 2 of the Hearing Protection Act, completely removing suppressors from the National Firearms Act (NFA).

Armed Churchgoers Prevent Mass Attack as State Lawmakers Plot More Gun Control

News  

Monday, June 30, 2025

Armed Churchgoers Prevent Mass Attack as State Lawmakers Plot More Gun Control

Just over an hour away from the state capitol in Lansing, Michigan – even as lawmakers worked feverishly to pass various gun control measures, including expansion of “gun free” zones – a chilling reminder unfolded of the ...

Urge the U.S. Senate to Pass the One Big Beautiful Bill – Contact Your U.S. Senators Today!

News  

Monday, June 30, 2025

Urge the U.S. Senate to Pass the One Big Beautiful Bill – Contact Your U.S. Senators Today!

The U.S. Senate has cleared a number of procedural hurdles and is preparing to vote on the One Big Beautiful Bill. This vote will likely come within the next day. The One Big Beautiful Bill includes ...

U.S. Court of Appeals Backtracks on Adverse Suppressor Ruling

News  

Monday, June 23, 2025

U.S. Court of Appeals Backtracks on Adverse Suppressor Ruling

In a single sentence, the U.S. Court of Appeals for the Fifth Circuit added to the high-profile and consequential national conversation on firearm suppressors.

Canada’s Big Ugly Gun Grab: An Update

News  

Monday, June 30, 2025

Canada’s Big Ugly Gun Grab: An Update

Canada’s Liberal government is pressing on with its harebrained gun ban and confiscation program for “assault style weapons,” but, true to form and precedents, it has been far from smooth sailing.

North Carolina: Update on Gun Bills Moving through the General Assembly

Tuesday, June 24, 2025

North Carolina: Update on Gun Bills Moving through the General Assembly

Recently, House Bill 193 (H193) was reported favorably out of both the Senate Judiciary Committee and the Senate Rules Committee, with amendments.

News  

Second Amendment  

Friday, June 27, 2025

Joint Statement from Pro-Gun Groups on the Senate Reconciliation Bill

On behalf of millions of NRA members and gun owners, we stand united in calling on Congress to uphold Americans' Second Amendment rights and zero out the NFA's excise tax on suppressors and short-barreled firearms.

Argentina President Milei Continues to Make Improvements to Country’s Gun Laws

News  

Monday, June 30, 2025

Argentina President Milei Continues to Make Improvements to Country’s Gun Laws

We’ve reported before about Argentina President Javier Milei expanding access to firearms for law-abiding Argentinians.

MORE TRENDING +
LESS TRENDING -

More Like This From Around The NRA

NRA ILA

Established in 1975, the Institute for Legislative Action (ILA) is the "lobbying" arm of the National Rifle Association of America. ILA is responsible for preserving the right of all law-abiding individuals in the legislative, political, and legal arenas, to purchase, possess and use firearms for legitimate purposes as guaranteed by the Second Amendment to the U.S. Constitution.