FIGURE 4.
Causal directed acyclic graph showing a variable as a collider on an open path from to in the eligible population. Selection into the study is or a descendant of . The dashed lines indicate open paths whose structure is not specified.
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.