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.
Liebler CA, Porter SR, Fernandez LE, Noon JM, Ennis SR.Liebler CA, et al. Among authors: noon jm.Demography. 2017 Feb;54(1):259-284. doi: 10.1007/s13524-016-0544-0.Demography. 2017.PMID: 28105578Free PMC article.