The United States now has more guns than people, according to estimates published last year in the Washington Post. But even before that disconcerting nugget of information entered the public realm, the U.S. still housed a rather obscene amount of firearms. Though nearly a decade old, the Small Arms Survey of 2007 still offers the most rigorous count of civilian gun ownership worldwide. The U.S. easily placed first, with approximately 88.8 guns per 100 individuals. Yemen came in a distant second with 54.8 firearms per 100 people.

The large number of guns in the United States has prompted a great deal of discussion. Is the rate of firearm ownership linked to homicide? What about crime in general? Owing to the often immeasurable variables that confound large societal studies, it's difficult to arrive at a clear answer. Even systematic reviews examining a wealth of research disagree.

Here's what we do know. After peaking in the 1980s and early 1990s, crime has plummeted in the United States. The rates of forcible rape, murder, violent crime, property crime, and aggravated assault are currently as low as they were in the 1960s.

While these statistics demonstrate that Americans are about as safe from crime as they have been in over a half-century, there is a particularly horrendous type of crime that has been alarmingly on the uptick: public mass shootings. In places like San Bernadino, California, Colorado Springs, Colorado, Roseburg, Oregon, Charleston, South Carolina, and Newtown, Connecticut, innocents have been mercilessly gunned down in great numbers.

Calls to reduce the availability of guns have followed in the wake of these tragic events. But yet to be determined empirically is whether or not gun ownership is even correlated to public mass shootings. Adam Lankford, an Associate Professor of Criminal Justice at University of Alabama, addresses that question with forthcoming research in the journal Violence and Victims.

In his study, Lankford combined data from the New York City Police Department’s (NYPD) 2012 Active Shooter report (PDF), the FBI’s 2014 active shooter report (PDF), as well as "data gathered on incidents from other countries" in an attempt to count all public mass shootings occurring between 1966 and 2012 in which at least four victims were killed. In total, Lankford tallied 292 incidents from 171 countries.

Lankford then explored how the number of mass shootings per country were associated with each country's homicide rate, suicide rate (used a rough proxy for mental health), and firearm ownership rate. While he found no link between the number of shootings and suicide or homicide rates, he found a highly significant (p<.01) link between the number of shootings and firearm ownership rates. In countries with more guns, there were more public mass shootings. The association remained even when the United States -- a clear outlier with 90 mass public shootings -- was removed from the data set.

"Many of the nations in this study that ranked highest in firearm ownership rates also ranked highly in public mass shooters per capita," Lankford notes. "For example, the Small Arms Survey (2007) lists the United States, Yemen, Switzerland, Finland, and Serbia as the top five countries in civilian firearm ownership rates, and all five countries also ranked in the top 15 in public mass shooters per capita."

Lankford noted a number of limitations to his study. Older incidents occurring further in the past and in countries without streamlined reporting systems may have been missed. Moreover, since public mass shootings are rare, the sample size is small for the forty-six-year study period.

Lankford also made clear that he utilized the definition of public mass shooting from the NYPD's report. The attacks "must have (a) involved a firearm, (b) appeared to have struck random strangers or bystanders and not only specific targets, and (c) not occurred solely in domestic settings or have been primarily gang-related, drive-by shootings, hostage-taking incidents, or robberies."

For the most part, Lankford steered clear of speculation in his study, preferring to leave that to the political and policy arenas. "I don't want the findings or their implications to be misunderstood," he told RCS in an email.

He did however, state the natural conclusion from his findings.

"Perhaps the most obvious step the United States could take to reduce public mass shootings may also be the most politically challenging: reduce firearms availability."

Lankford noted that the approach seemed to work in Australia. After a public mass shooting in 1996 that left thirty-five people dead, the country's government passed comprehensive gun control legislation. Decades later, firearm homicide and suicide rates are way down, and there have been no more public mass shootings.

He ended his article with a plea for further research.

"Ultimately, more cross-national studies of public mass shooters could help ensure that future strategies for prevention are based on reliable scientific evidence. Some countries and cultures are clearly safer than others; it would be a shame not to learn from them."

Source: Lankford, Adam. "Public Mass Shooters and Firearms: A Cross-National Study of 171 Countries." 2016. Violence and Victims. http://dx.doi.org/10.1891/0886-6708

(Image: AP)