Table 1
Some Examples of Re-identification Attempts in General Data Sets and of Health Data Sets*
| General Examples of Re-identification | |
| AOL search data29 30 31 | AOL put anonymized Internet search data (including health-related searches) on its web site. New York Times reporters were able to re-identify an individual from her search records within a few days. |
| Chicago homicide database32 | Students were able to re-identify a significant percentage of individuals in the Chicago homicide database by linking with the social security death index. |
| Netflix movie recommendations33 | Individuals in an anonymized publicly available database of customer movie recommendations from Netflix are re-identified by linking their ratings with ratings in a publicly available Internet movie rating web site. |
| Health-specific Examples of Re-identification | |
| Re-identification of the medical record of the governor of Massachusetts34 | Data from the Group Insurance Commission, which purchases health insurance for state employees, was matched against the voter list for Cambridge, re-identifying the governor's record. |
| Southern Illinoisan vs. The Department of Public Health35 36 | An expert witness was able to re-identify with certainty 18 out of 20 individuals in a neuroblastoma data set from the Illinois cancer registry, and was able to suggest one of two alternative names for the remaining two individuals. |
| Canadian Adverse Event Database37 | A national broadcaster aired a report on the death of a 26 year-old student taking a particular drug who was re-identified from the adverse drug reaction database released by Health Canada. |
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↵* The former type of data can contain health information (as in the case of the individual re-identified in the AOL example), and life style and sexual orientation information (as in the case of one of the individuals re-identified in the Netflix example).
