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.
Network diagram for the smoking cessation data. Node size is proportional to the number of trials including the treatment, and multi-arm trials are shown as closed loops. Treatments are A: no contact, B: self-help, C: individual counselling and D: group counselling.
