September 22, 2011

How many U.S. residents were missed in the census?

Q. My wife and I did not receive the 2010 census form and were not polled/interviewed/counted. How many U.S. residents were missed in the census?

The 2010 Census certainly did miss some people; in that respect, it is like every other census. The Census Bureau conducted an independent follow-up survey in order to estimate how many people were not included. Results will be published next year. Some other quality indicators already are out — for example, the bureau said it obtained at least some useable information from 99.62% of the nation’s housing units, an increase from 99.45% in 2000.

If the Census Bureau does not receive a completed form from a particular address, and census-takers cannot reach anyone there after multiple visits or calls, the agency tries to obtain information about the household from neighbors or a building manager. If that fails, the Census Bureau resorts to a last-ditch statistical technique called “imputation” to fill in the missing data. As this article on our “All Things Census” page explains, agency analysts use imputation when they do not even know whether someone lives at a particular address, when they know someone lives there but not how many people, and when they know how many people live somewhere but do not know their race or other characteristics. Imputation is based on what bureau analysts know about the size and type of neighboring households. In the 2010 Census, 1.16 million people were added to the count through imputation, or .39% (less than half a percent) of the total.

D’Vera Cohn, Senior Writer, Pew Research Center