A Cluster of Smokers in a Face-to-Face Network in 2000

This graph shows a close-up of a cluster of nodes from the Framingham Heart Study Social Network in the year 2000. Each circle (node) represents one person. Circles with red borders denote women, and circles with blue borders denote men. The interior color of the circles indicates the person’s cigarette consumption (yellow denotes ≥1 cigarette per day, and green denotes no cigarettes). The size of each circle is proportional to the number of cigarettes consumed. The colors of the ties between the circles indicate the relationship between them: orange denotes a friendship or a marital tie, and purple denotes a familial tie. Smokers are more likely to appear at the periphery of their networks. For more details, see: N.A. Christakis and J.H. Fowler, “The Collective Dynamics of Smoking in a Large Social Network,” New England Journal of Medicine 2008; 358: 2249-2258.