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.
(A) Risk of bias graph. (B) Risk of bias summary. Green box/node represents low risk of bias, yellow box/node represents unclear risk of bias, and red box/node represents high risk of bias.
