What are the best ways to discourage smoking? That question sometimes invites excited conversation when I ask it, but a new study from international tobacco control researchers has an answer.

The most effective: graphic warning labels on packages, bans on cigarette advertising and increasing cigarette prices are some of the most effective ways to curb smoking.

An ineffective approach: mandating tar and nicotine levels in cigarettes, which is a weak approach to begin with since it's mostly passive.