Fig 1. Friendship networks.
(1A) A smoker’s friendship network and (1B) a nonsmoker’s friendship network are shown with ego, without ego, and with communities drawn after excluding ego and isolates.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.