In a new study published in Science, a group of researchers from the Human Dynamics group led by student Yves-Alexandre de Montjoye, found that "anonymized" credit card users could be reidentified with just a few pieces of information. The researchers analyzed transactions made by 1.1 million people in 10,000 stores over three months. Although the information had been “anonymized” by removing names and account numbers, each purchase made by the same credit card was tagged with the same random identification number. Using this number, the researchers were able to use just three more pieces of data—the date, location, and price of each transaction—to reidentify 90 percent of individual consumers.

Learn more about this project in the following press coverage:
Privacy Challenges (MIT News)

With a Few Bits of Data, Researchers Identify ‘Anonymous’ People (The New York Times)

Analysis Suggests That Making Data Anonymous is Not Enough to Protect Consumers (Nature)

Your Shopping Habits are One in a Million, Literally (The Verge)