The Collective Dynamics of Smoking in a Large Social Network

The prevalence of smoking has decreased substantially in the United States over the past 30 years. This article examines the extent of person-to-person spread of smoking behavior and the extent to which groups of widely connected people quit together. Smoking behavior spreads through close and distant social ties, groups of interconnected people quit in concert, and smokers are increasingly marginalized socially. This article examines the extent of person-to-person spread of smoking behavior and the extent to which groups of widely connected people quit together. Roughly 44.5 million adults were smokers in the United States in 2004, 1 and smoking remains the leading preventable cause of death, 2 with 440,000 deaths annually. 3 Nevertheless, the prevalence of smoking has declined from 45% to 21% over the past four decades. 4 Past studies have documented the impact of dyadic social ties on the initiation and cessation of smoking, primarily in young people. 5 , 6 However, the extent to which smoking depends on how people are embedded in a social network and the extent to which smoking behavior transcends direct dyadic ties are not known. Since diverse phenomena can spread within social . . .