An official website of the United States government
Here’s how you know
Official websites use .gov A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS A lock ( Lock A locked padlock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
This document describes the new imputation methodology first used in 2017.
Share
Some content on this site is available in several different electronic formats. Some of the files may require a plug-in or additional software to view.
