"Fred Rivara, an epidemiologist at the University of Washington, added in an email: “There is no data supporting his argument that the further arming of citizens will lessen the death toll in massacres like the one this week in Connecticut. There are in fact rigorous scientific data showing that having a gun in the home INCREASES the risk of violent death in the home.”
"Researchers at Johns Hopkins University recently conducted a review of all the existing academic literature on right-to-carry and found: “The most consistent finding across studies which correct for these flaws is that RTC laws are associated with an increase in aggravated assaults.” They estimated the increase to be about 1 to 9 percent, which may not sound like much — but with nearly 1 million aggravated assaults in the country every year, a small percentage change makes a big difference.
Researchers at Harvard have conducted numerous studies comparing data across states and countries with different gun laws and concluded, quite simply, “Where there are more guns, there is more homicide.”
Daniel Webster, the director of the Johns Hopkins Center for Gun Policy and Research, explained in an interview: “It’s hard to make the case, as some have done, that right-to-carry laws will lead to an enormous increase in violence. That does not appear to be the case. But it also does not appear to be the case that there is any beneficial effect.”
Colin Goddard, who became an advocate with the Brady Campaign after getting shot multiple times at the Virginia Tech shooting, put it another way: “If more guns would lead to less crime, then why is America not the safest place in the world, with 300 million guns?”
Garen Wintemute, a public health researcher at the University of California, Davis, said in an interview that this leads to faulty conclusions. “Everybody is talking about how do we stop the next Sandy Hook, but that’s the totally wrong approach, because the next one will be totally different,” he said.
"More important, while mass shootings like the one in Newtown are always the catalyst for a debate over guns, they’re a tiny fraction of the problem. There are about 20 mass shootings a year in this country, which altogether take the lives of perhaps several hundred people. But there were over 32,000 firearm-related deaths last year, the majority of which (almost 20,000) were suicides. There were also almost 850 accidental deaths from firearms. Among homicides, “far more common than mass killings are altercations where, because there is a gun available, someone ends up dead instead of a less lethal option,” Wintemute said."
The answer is not more guns - Salon.com
