https://ischoolonline.berkeley.edu/blog/anonymous-data/
QT:{{”
The classic example of this problem occurred in 1997, when Latanya Sweeney, who was then a graduate student at MIT, found the medical records of Massachusetts Governor William Weld, who had collapsed during a public ceremony. She used Weld’s readily available zip code and birth date to scan the Massachusetts Group Insurance Commission (GIC) database for his records and confirmed the identity using voter-registration records from Cambridge, Massachusetts. Some have cited this as an unusual example, given that it involved a
high-profile public figure, which may not be generally repeatable. However, at the American Association for the Advancement of Science meeting in Chicago earlier this month, Sweeney, who is now a computer science professor at Harvard, submitted the results of another sting operation: This time, she purchased a $50 database from the state of Washington that included all hospitalization records for one year. The data included patient demographic information, diagnoses, the identity of the attending physicians, the hospital, and the method used to pay the bill. It had no patient names or addresses, but it included the zip code. Sweeney then conducted a search of all news stories in the state that contained the word ‘hospitalized’ during the same period. With a little sleuthing, they found they could exactly match the information from an article to the database in 43 percent of the cases (they hired a reporter to confirm the identifications), essentially allowing them to place a name on an anomymized health record. “}}