Does owning a gun change your behavior?

When you think of gun violence, you might picture a criminal wielding a 9 mm pistol at an unsuspecting victim or a homeowner using a shotgun to defend himself from an intruder, but the majority of gun deaths in the U.S. aren't from assaults but people using guns to take their own lives [source: Sapien]. In 2011, the most recent statistical year available, 19,766 people in the U.S. committed suicide with a firearm. Meanwhile, 11,101 committed homicide with a firearm [source: Hoyert and Xu].

In Mindy McCready's case, it's pretty easy to argue that without a gun she might have found some other way to take her life. Police also found bottles of prescription medications in her home [source: People Magazine].

But there is a connection between owning a gun and taking one's own life. A Centers for Disease Control and Prevention (CDC) 2004 survey of gun violence research published in the American Journal of Epidemiology found that gun owners who committed suicide were more likely to use their guns rather than other methods, like pills. A 1992 study cited in the CDC survey discovered that people with a gun in the home were five times more likely to commit suicide overall. And a large-scale, national 2003 study found that access to a gun made a person more than three times more likely to commit suicide than someone without firearms [source: Dahlberg, Ikeda and Kresnow].

Why would that be? Experts posit that suicide is often an impulsive act, occurring when a person is suffering an acute crisis. Eighty-five to 90 percent of people who shoot themselves succeed in dying, a much higher rate than with any other method of suicide. Arguably, if people did not have access to guns during that extreme period in their lives, it is likely they'd still be alive. In fact, the Israeli Defense Force found it lowered the suicide rate 40 percent among its soldiers simply by forbidding them from taking their weapons home over the weekend [source: Neyfakh].

It's pretty clear that owning a gun puts you at higher risk for harming yourself, but what about harming others?

A lot of the government-funded research on gun violence comes from the early to mid-1990s. That's because in 1996, the National Rifle Association successfully lobbied Congress to cut funding for gun violence studies. But before that, the CDC found that having a gun in the home made homicide about three times more likely for family members in that house [source: Sapien]. This jibes with a 1992 study, which found that family disputes that turned violent were three times more likely to result in death when a firearm was present versus other weapons [source: Saltzman].

Most homicides aren't carefully planned events. Instead, an argument with a friend or family member -- maybe over money or infidelity -- turns violent. Add a gun to the mix and the chances of death are greater than say, using a baseball or a knife.

But researchers point out that the correlation between homicide and firearms in the house is not as strong as the relationship between suicide and firearms in the house. Most murder victims are not shot at home – unless they are women, children or elderly. Also households with gun ownership might be more engaged in criminal activity. But one often-cited study of 400 homicide victims who were killed in their homes showed that half died of gunshot wounds and in the vast majority of cases, they knew the perpetrator. Forced entry was rare – only 14 percent of the time. Thirty-six percent of these homes owned firearms versus 23 percent of control households [source: Hemenway].

The change in behavior extends to the street. A 2009 study looked at 677 shootings in Philadelphia over two-and-a-half years and found that people who carried guns were 4.5 times more likely to be shot and 4.2 times more likely to be killed as unarmed people. The study authors think that guns may give their owners a sense of empowerment that leads them to act rashly or go into dangerous situations or places they might otherwise avoid [sources: Callaway,Branas].