Figure 7.
Colliding bias superimposed on confounding bias in a matched case-control study.
Note: The question mark denotes the effect of interest.
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.