Figure 1. The Percentage of Citations Placed in Each Variable Group by Transmission Mode (if a model contained variables from multiple groups, it was placed in each respective group).
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.