An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Thygesen SK, Christiansen CF, Christensen S, Lash TL, Sørensen HT.Thygesen SK, et al. Among authors: christiansen cf.BMC Med Res Methodol. 2011 May 28;11:83. doi: 10.1186/1471-2288-11-83.BMC Med Res Methodol. 2011.PMID: 21619668Free PMC article.