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.
Study classifications [54]
| Category | Study characteristics |
|---|---|
| Key papers | Conceptually rich with the potential to make an important contribution to the synthesis |
| Satisfactory papers | Less valuable than key papers but still relevant |
| Questionable papers | Uncertain contribution |
| Irrelevant | Not relevant to the review question |
| Fatally flawed | Study data not presented in a usable format |
