Nice article on research that shows how Quitting smoking travels (like practically everything else) through social networks of people who know each other.
P.S. We keep being surprised by this kind of research, but the insight goes right back to the very start of diffusion research… a simply written, plain English, article written by Bryce Ryan and Neal Gross in a humble rural sociology journal in 1943…
To see it, go to http://chla.library.cornell.edu then search under “diffusion” with the author names “Ryan” and “Gross”. Their article is in Rural Sociology Volume 8.