This is done using a technique indicating a kind of bias by story selection. If someone wants to run a story on the drastic decline in school shootings that has been occurring over the last several decades, but someone else wants to run a story on a recent school shooting, the recent school shooting story will be given the go-ahead. The aim of this is to passively give the audience the impression that, because an event is "newsworthy," it is a common event. Never mind that, for every report that makes it to air, there are probably hundreds, if not thousands of other potential stories; only the ones that actually make it scale up to the bigger picture of society at large.
Most people don't travel very far in their daily lives. Even taking into account commutes to work that are an hour or two long, few people work several states away from their place of residence, let alone across the country -- or across the world. Additionally, the average person tends to selectively absorb information that is most beneficial for him or her to absorb; if you like football, you're not going to actively seek out information about cricket, and if you're a Christian, you're not going to actively seek out information about Islam, or Norse paganism. Are you a big fan of heavy metal? If you are, you're statistically unlikely to read up on post-war jazz or psychedelic trance.
What this seems to imply is that, because most of us are so stubbornly attached to those artifacts of culture which define us as individuals, all that the media has to do is present us with a few incidents while selectively ignoring contrary incidents, and we'll just assume that the world "is" the way that the media has decided to portray it this time. We're too ignorant and lazy to peer review what the media presents us with.
To most people, there are only a few types of music: rock, rap, pop, jazz, classical. To most people, there are only a few religions: Christianity, Islam, Judaism, Buddhism, Hinduism. To most people, there are only a few political ideologies: conservatism, liberalism, libertarianism, centralism. To most people, there are only a few things happening in the world in general, and almost all of the "important" ones make it to our televisions and computer screens.
We tend to forget just how large the number "one million" really is, let alone "one billion." The speed with which information gets to us makes us feel as though the world is far smaller than it actually is; the consequence is that the dozen or so worldly events that we hear about during a month come to paint a picture of a small, physical landscape where such events predominate, and the organizations in charge of presenting us the events can pick and choose at their leisure.
There are a few reasons for why the media might want to passively suggest to the American public that we're facing some kind of "mass killing" epidemic:
1. Gun control advocates who want to ban all gun ownership outright
2. Pharmaceuticals companies who want to sell their products to psychiatric patients with arbitrary "mood disorders"
3. Lobbyists interested in censoring violence in popular media, like movies and video games
Perhaps the thousands of events reported to the police that we never hear about are not so much unrepresentative of social trends as they are irrelevant to a particular body's pursuit of wealth and power.
Here are some burglary facts:
1. More than seventy percent of burglaries occur during the daytime.
2. The favored time of day to commit a burglary is between 7:00 and 10:00 AM -- after you've gone to work and the kids have left for school. It's highly unusual for a burglar to actually run into his victim.
3. The majority of burglaries are the result of doors being left unlocked.
4. Many burglaries are perpetrated by neighbors.
5. Burglary is incredibly rare in the United States to begin with; out of around 112 million homes, only a little over 2 million get burglarized every year -- a little under two percent. Most of those burglaries occur in areas where job creation is difficult and crime is high in general, meaning that the majority of that 2 million figure will never leave the same concentrated metropolitan areas. In other words, if you've never been burgled, don't expect that to change anytime soon -- and if it does, you'll be several times more likely to be at work than waking up in a cold sweat at 4:00 AM from the hideous sound of your door being kicked in!
Movies, dramatized reenactments, and commercials aimed at getting us to buy junk will tell a different story, but the numbers don't lie.
So what about school shootings and other similar mass killings? Aren't quiet, skinny, geeky guys starting to lose their minds because of social withdrawal and violent video games?
Well, not really. School shootings have been going on since at least the 1970s, and there were more incidents involving gunfire on school property during the 80s than either the 90s or the 00s. The year before the Columbine massacre, an incident in Oregon left 22 wounded and 2 dead, but it was completely overshadowed by the Columbine story. Why is everyone familiar with "Eric and Dylan" but not ol' Kip Kinkel? Could it be because he struggled in school and wound up enrolled in special education courses? That's not exactly the typical picture of a smart, withdrawn guy going crazy; you can't push an agenda when the perpetrator doesn't fit into your view of the trend.
Here's what the National School Safety Center has to say about gun-related deaths in schools during the 90s:
1992–1993 (44 Homicides and 55 Deaths resulting from school shootings in the U.S.)
1993–1994 (42 Homicides and 51 Deaths resulting from school shootings in the U.S.)
1994–1995 (17 Homicides and 20 Deaths resulting from school shootings in the U.S.)
1995–1996 (29 Homicides and 35 Deaths resulting from school shootings in the U.S.)
1996–1997 (23 Homicides and 25 Deaths resulting from school shootings in the U.S.)
1997–1998 (35 Homicides and 40 Deaths resulting from school shootings in the U.S.)
1998–1999 (25 Homicides from school shootings in the U.S.)
1999–2000 (25 Homicides from school shootings in the U.S.)
Quite a drop! Even if the numbers start to go back up someday, just remember that the increase is terribly, terribly insignificant. What if, say, one hundred school massacres occur next year, in contrast to the four or five that have happened so far this decade? There are nearly 100,000 public schools in the United States, so even that highly significant increase would only amount to a 0.1% likelihood of you ever seeing a gun in your school (right now, it's something like 0.006%).
This is stupid. Considering the outright disappearance of pistol duels among gentleman and riots instigated by unruly gangs -- phenomena once prevalent in the 18th and 19th centuries -- violence is just about the least of our concerns today. Why don't we start reporting on things that matter -- like false medical diagnoses, increases in anxiety disorders, alcohol-related suicides, or, you know, the fourteen percent of the species that's starving to death?