Medical researchers have treated gun ownership and use as a public health issue, looking at the risk to the public at large from the presence of guns. However, social scientists question using an epidemiological approach, in which violence is treated like a disease and guns are treated like a cause. They suggest the situation is much more complex.

For example, studies by Arthur Kellermann, a physician, claim that gun-owning households, compared with gunless ones, are almost three times as likely to be the scene of a homicide and almost five times as likely to be the scene of a suicide. However, social scientists interpret his data differently:

• Households in which homicides took place were more likely to contain a family member who abused alcohol or drugs and had a history of domestic violence.
  
  

• These factors contributed to the likelihood of homicide independent of the presence of guns in the home.
  
  

• Kellermann statistically manipulated his figures to account for these factors; however even he admits the possibility that some other factor might be present.

Critics also suggest that the victims in Kellermann's study may have gotten guns because they felt themselves threatened, which means they might have suffered higher homicide rates even if they hadn't bothered to arm themselves.

Further, suicide is prone to substitution -- although guns are the preferred instrument in the United States, a person bent on suicide can easily find a substitute. But Kellermann didn't account for victims without guns who went outside the home to kill themselves, say, by jumping off a bridge.

On the other hand, social scientists such as Gary Kleck, of Florida State University, have used surveys to estimate that guns are used (though not necessarily fired) in self-defense 2.5 million times each year. But "defensive gun use" is a broad term, so the data are open to different interpretations.

Source: Fred Guterl, "Gunslinging in America," Discover, May 1996.