ELEANOR HALL: As the US struggles to deal with its latest mass shooting, crime analysts are warning that the way the media covers events like this can increase the likelihood of future shootings.

The number and severity of mass shootings in the US has increased significantly in the last decade and a half.

Dr Jennifer Johnson is a researcher at Western New Mexico University who has been examining the data.

JENNIFER JOHNSON: What we found is mass shootings are on the rise in the United States. In the last 15 years we were able to calculate that there is indeed a three-fold increase. And so that made us question: why? What could be causing that?

We find that there are shared traits among most active shooters or, sometimes, mass shooters. Generally, depression - a suicidal type of depression - social isolation and narcissism. They identify with each other and when they see someone in the media who is being given the fame that they seek, that someone who is considering an act like this in fantasy, or even had some plans laid out who might not have otherwise committed those acts, does so because they identify with another shooter and feel motivated to either best that shooter's kills or make a name for themselves as they go out in a "blaze of glory".

ELEANOR HALL: So you have no doubt that media coverage is driving the increase in mass shootings in the United States?

JENNIFER JOHNSON: There is strong suspicion. The reason is that, when we look at the other major causal factors involved in mass shootings - access to guns and lax gun laws; if we look at the mental health system and how mental illness is reported or intervened; and then if we look at media contagion - the only thing that has really changed in the last 15 years - and really about 20 years - is media coverage of the events.

We have much more coverage in 24-hour news cycles as well as, of course, the birth of the internet in this time period. And so we think that that may be part of the reason to explain the increase in the contagion effect.

ELEANOR HALL: You mentioned that there has been a dramatic increase in mass shootings. What are the actual numbers?

JENNIFER JOHNSON: Before the year 2000 there were up to about 50 deaths related to mass shootings a year. We're now topping more like 300 deaths per year.

ELEANOR HALL: That's a six-fold increase.

JENNIFER JOHNSON: Yeah. It's significant in the number of deaths. And so, and then when we also count - that's the number of deaths, but if we count incidents: those have risen three-fold in a 15-year period. That is startling.

ELEANOR HALL: So you are calling on media organisations to adopt a code of reporting, similar to our codes on reporting suicides.

JENNIFER JOHNSON: Exactly.

ELEANOR HALL: What ideally should or shouldn't the media be doing when it's reporting events like this Las Vegas shooting?

JENNIFER JOHNSON: What we recommend - and for example, one of the parents of a Columbine victim first suggested to the media: a 'don't name them' campaign. And that had something to do with respect for the victims and their families.

They didn't want to be hearing and seeing the perpetrator's names everywhere and kind of being given that attention in place of victims, because one of the issues we have found is that media coverage is about double for shooters than it is for victims, first responders or even, say, causes of murder.

So we know that that is happening: much more attention on the shooter than on the people who, maybe, we should be giving attention to.

The media is, of course, not intentionally trying to do any of this. They're just covering the news as best they can with the detail that they think the public wants.

But the FBI adopted this campaign and has promoted it within their briefings to the news media. But a lot of times, you know, the information gets out anyway.

But we believe that if you don't name the shooter and you don't show his image - and also, if possible, details about their intimate lives, histories, interests, weapon choices, those kinds of things: the details that a would-be shooter can identify with and see themselves in and want to emulate.

ELEANOR HALL: And what about the descriptor of this particular shooting: "The worst mass shooting ever"? Is that something also that we should be avoiding?

JENNIFER JOHNSON: I believe so. We have heard and we have read in some of the manifestos of previous shooters that they are trying to become the next, greatest known shooter by number of deaths. And so they seem to be trying to best each other.

And so we do see these headlines of: yeah, "The most deadliest shooting in history." And that seems to be something that motivates shooters as well to get more powerful weapons that have larger magazines and can do more damage in shorter time.

ELEANOR HALL: There is obviously a lot of interest from the public in why they have done it. How do you balance that public interest with what you're talking about: the potential contagion?

JENNIFER JOHNSON: Well, there's a certain point where we all have to ask ourselves: are we going to let our fascination for something drive us to do something that could be making a problem worse? It just becomes an ethical issue for us as viewers and for the media, too.

In fact, it reminds me of the study about tweets. So social media has an impact on this as well: that when tweets rise above 10 per million talking about a mass shooting in a certain area, it increases the likelihood of another mass shooting 50 per cent in the next two weeks. And if it continues to rise above 10 tweets per million, the odds go to 80 per cent that another shooting will happen within 30 days.

What we suggest is: the media can always talk about shooters in aggregate. You can talk about traits of shooters; like I said, those shared traits that they seem to have; causes that may be going on underneath this issue.

So there's a lot, I think, the media can cover without giving in to what the shooter really seems to be after, which is fame.

ELEANOR HALL: But you're convinced that, if media organisations were to change the way we report mass killings, like this one in Las Vegas, there would be a reduction in shootings?

JENNIFER JOHNSON: Yes. We believe that, if the mathematical contagion model is correct, we would see up to about a one-third reduction in mass shootings over the next one to two years: a fairly quick response, I believe, if those models are correct.

ELEANOR HALL: That's a remarkably short space of time.

JENNIFER JOHNSON: Yes. And of course, we're speculating. But it takes away the carrot.

And we think if the shooters and would-be shooters start realising that they will only be killing themselves and no-one will know their name, no-one will remember them in history - we'll remember the victims and what happened and how the community responded, but that only the police departments will ever know their name - we think that it may discourage future shooters.

ELEANOR HALL: That's Dr Jennifer Johnson from Western New Mexico University.