Fig. 2.
Directed acyclic graph showing the relationships between variables included in the model and additional variables that could have played a role in the relationship between spread of H5N1 between countries.
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.