Follow up to previous postings on gun violence, via Marc Parrish/The Atlantic:"Big data might have stopped the massacres in Newtown, Aurora, and Oak Creek. But it didn't, because there is no national database of gun owners, and no national record-keeping of firearm and ammunition purchases. Most states don't even require a license to buy or keep a gun. That's a tragedy, because combining simple math and the power of crowds could give us the tools we need to red flag potential killers even without new restrictions on the guns anyone can buy. Privacy advocates may hate the idea, but an open national database of ammunition and gun purchases may be what America needs if we're ever going to get our mass shooting problem under control."