The shocking murder of two journalists carried out on live television this week has Americans once again asking questions about why these kinds of crimes seem to happen with such frequency in their country.

Three people were shot, two of them died and the gunman killed himself in Roanoke, Va.

A few days before the shooting, researcher Adam Lankford was at the American Sociological Association's conference in Chicago presenting his study that found the U.S. leads the world in mass shootings.

His findings are even more relevant following Wednesday's events in Virginia, even though the deaths of Alison Parker and Adam Ward, journalists at a Roanoke TV station, don't technically meet the definition of "mass shooting" — four or more victims.

The University of Alabama professor found that despite having less than five per cent of the world's population, the United States was home to 31 per cent of the world's mass shooters between 1966 and 2012.

His work discusses the reasons behind his finding, and in the context of the theory of American exceptionalism, he finds that there is indeed something uniquely American about mass shootings.

They are "an exceptionally American problem," he writes.

Using data compiled by the New York City Police Department in its 2012 report on active shooting incidents in the U.S. and around the world, as well as data from a 2014 FBI report, Lankford determined that the U.S. had 90 mass shooting incidents during that time frame.

That's more than five times the number of second-place finisher the Philippines. Russia, Yemen and France followed in that order. Another finding about the U.S. stood out: Of the cases reviewed worldwide, 62 per cent of all school and workplace shootings happened within the U.S.

"Overall, some combination of American exceptionalism, American gun culture, and American strains could potentially explain the commonality of public mass shooters in the United States," Lankford writes.

There are limitations to this study, Lankford noted in an interview.

For example, he only included shootings where four or more people were killed, and only looked at active or rampage shooter situations — killings in workplaces or movie theatres, for example, not gangs battling it out on a street.

Many Americans take their constitutional right to bear arms very seriously, and Lankford's study points out that the U.S. ranks first out of 178 countries when it comes to gun ownership. A 2007 survey showed Americans own 88.8 guns per 100 people. Canada ranked 13th, but is not even close to the U.S. with 30.8 guns per 100 people.

Failing to achieve 'the American dream'

America's gun culture and the widespread availability of firearms, contributes to the country's mass shooting problem, the study says. It found that American mass shooters were more likely to arm themselves with multiple weapons, though they killed fewer people than shooters in other countries.

Lankford said that may be because law enforcement is so accustomed to mass shootings now in the U.S. that they can respond faster and with more established procedures to prevent more casualties than in other countries.

While Lankford's study suggested a strong link between the civilian firearm ownership rate and the number of public mass shooters in the United States, he said there could be other factors that make the U.S. especially prone to public mass shooting incidents.

America puts more pressure on its citizens to succeed professionally and financially than other countries, Lankford discusses in his study, and when Americans have bad experiences at work or school and fail to achieve their goals, they are more likely to respond with acts of violence.

Aurora theater killer James Holmes was found guilty of the mass shooting in August and sentenced to life in prison. (Andy Cross/The Denver Post/Associated Press)

"Notably, these strains seem to transcend age and class. In America, students, adults, blue-collar workers and white-collar workers may all be somewhat more susceptible to the social pressures that, in extreme cases, can lead to mass shootings," he writes.

Different cultures define success in different ways, and while Canadians and Americans might seek the same things in life, achieving "the Canadian dream" isn't a national ethos the way "the American dream" is south of the border.

"I'm not an expert on Canadian culture or history, but the American dream has carved out its own mythology and set of expectations," Lankford said.

Killers have often cited a failure to achieve a goal at work or at school, places where shootings happen more often in the U.S. than in other countries, as motivation for their crime, the study notes.

A focus on fame

Then there's also the idolization of fame, which appears uniquely American, according to Lankford. Increasingly in the U.S., especially among young people, becoming famous is considered the ultimate form of success.

"If being famous is one of your most important goals, it's setting up a lot of people to fail," he said in the interview.

"Unfortunately, due to some combination of strains, mental illness and American idolization of fame, some mass shooters succumb to terrible delusions of grandeur, and seek fame and glory through killing," his study says. They realize that the only way they will become a household name is by killing innocent people.

Lankford said understanding some of the social reasons that may contribute to the mass shootings problem in the U.S. is important for other countries such as Canada, given the degree to which American media and culture are exported around the world.

The Columbine shooters, for example, were considered vigilante heroes by other at-risk individuals in foreign countries who saw the fame the massacre brought them. The suspects in a plot to carry out a mass shooting in Halifax earlier this year were "Columbiners," devotees of the gunmen who carried out the 1999 school shooting in Colorado.

"If the lust for fame continues to spread from America to Canada, that would be something that people might need to watch out for," Lankford said.

He concludes in his study that the most obvious step to reduce mass shootings in the U.S. is to reduce the availability of guns — but that's an uphill battle politically. In the meantime, what is more realistic is trying to help those who are struggling to cope with their stress and their strains.

"For concerned citizens, this provides an opportunity to get them the help they so desperately need, and to thereby make the world both a safer and healthier place," Lankford said.