"[W]hen a robbery victim does not defend himself, the robber succeeds 88 percent of the time, and the victim is injured 25 percent of the time. When a victim resists with a gun, the robbery success rate falls to 30 percent, and the victim injury rate falls to 17 percent. No other response to a robbery -- from drawing a knife to shouting for help to fleeing -- produces such low rates of victim injury and robbery success."

David Kopel