Incident: A number is not an anonymous person

Module 2 · Incident file · About 35 minutes

What happened

In early August 2006 AOL posted about 20 million web search queries from roughly three months of use by its subscribers, for the benefit of academic researchers. Each subscriber's account name had been replaced by a number. The New York Times (Michael Barbaro and Tom Zeller Jr., "A Face Is Exposed for AOL Searcher No. 4417749", 9 August 2006) described what the number was for and what it was worth: it "was assigned by the company to protect the searcher's anonymity, but it was not much of a shield." User No. 4417749 "conducted hundreds of searches over a three-month period", and among them were queries for "landscapers in Lilburn, Ga", "several people with the last name Arnold" and "homes sold in shadow lake subdivision gwinnett county georgia". "It did not take much investigating to follow that data trail to Thelma Arnold, a 62-year-old widow who lives in Lilburn, Ga." Her reaction: "My goodness, it's my whole personal life. I had no idea somebody was looking over my shoulder."

The release was noticed on a Sunday and AOL apologised on the Monday (TechCrunch, 9 August 2006). AOL "removed the search data from its site over the weekend", calling it "an unauthorized move by a team that had hoped it would benefit academic researchers", but copies "continue to circulate online", with the records of "Ms. Arnold and 657,000 other Americans". AOL's spokesman said the company had "acknowledged that there was information that could potentially lead to people being identified, which is why we were so angry." On 21 August the Associated Press reported that two employees had been dismissed and the chief technology officer had left; the queries, it said, "contained Social Security numbers, medical conditions and other data that could be traced to an individual" (AP via NBC News, 21 August 2006).