White House warns of open data mosaic effect

"Consistent with previous Obama administration guidance, the Open Data Policy published by the White House May 9 says the privacy and security of open data is the responsibility of the releasing agency. Beyond asking agencies to guard against the release of data with personally-identifiable information, the policy directs agencies to account for the "mosaic effect" of data aggregation. The mosaic effect occurs when information alone is not identifiable but when coupled with other available information poses a privacy or security risk...."