| Category 1: | true outcome events that cannot be contaminated by ascertainment bias, |
| Category 2: | events that should meet the outcome definition but may fail to in the presence of ascertainment bias, and |
| Category 3: | events that should not meet the outcome definition and can be mimicked by Category 2 outcomes via bias. |
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.