re-identification
n. The process of matching anonymous census data with the individuals who provided the data.

Example Citation:
In a corner of the U.S. Census Bureau, a small group of statisticians has been sweating out the agency"s nightmare scenario: "re-identification." That"s the term for a technique that the bureau fears could allow marketers and other “intruders“ to match anonymous census information with the names of the people who provided it. Such a concern is largely theoretical, so far. But if perfected, the technique could have great appeal to marketers of everything from french fries to financial services.
—Glenn R. Simpson, “The 2000 Count: Bureau Blurs Data To Keep Names Confidential,“ The Wall Street Journal, February 14, 2001

Earliest Citation:
Bernstam"s corrections are straightforward. The practice of the Soviet census has been to have the citizen himself indicate his nationality, and to allow him freedom of identification and “re-identification“.
—Dr Stefan T. Possony, “On The Russian Demographic Changes,“ Defense & Foreign Affairs, May 1, 1983

Notes:
The Wall Street Journal article cited above also mentions the term data swapping, a technique in which important bits of census data are swapped between two people who live near each other and have similar backgrounds. This is a countermeasure against re-identification because it "blurs" the data, making it less attractive to marketing types and anyone else who might want to take advantage of the riches of a census:

The bureau for decades has engaged in a little-known technique called 'data swapping,' in which a few key pieces of information about one person are switched with those of another person with a similar background living nearby. The process allows researchers to continue to draw valid observations from the file, since the swapping doesn't change the totals for each data column within a census block.
—Glenn R. Simpson, "The 2000 Count: Bureau Blurs Data To Keep Names Confidential," The Wall Street Journal, February 14, 2001

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