This year has seen a handful of high-profile shootings, from Las Vegas to Sutherland Springs, Texas, and it’s also seen calls to end gun violence.

But some experts say doing that would require research — research the federal Centers for Disease Control and Prevention used to do, but no longer does.

Mark Rosenberg used to do that work, and he's here to talk about it. He was the founding director of the National Center for Injury Prevention and Control at the CDC but left the agency in 1999, after it stopped doing research into preventing gun violence.