The Brave New World is here. A new study published in the academic journal Science last week demonstrates that it is possible to positively identify individuals from as few as four “anonymous” credit card transactions.
The study examined three months of credit card records for 1.1 million people in an industrialized country to see if new Big Data analysis software could identify individuals using credit card transactions. In a scary development, it turns out 90% of the 1.1 million could be uniquely identified with just four pieces of information, such as where they bought coffee that morning or where they purchased a new shirt or pair of shoes.
The study determined that credit cards records are just as reliable at individual identification as mobile phone records.
Details on study of credit card records
It turns out that sophisticated Big Data analysis software can figure out an individual’s identity even if the data is made “anonymous”. Study authors Yves-Alexandre de Montjoye of the Massachusetts Institute of Technology and colleagues at Aarhus University in Denmark noted: “Even data sets that provide coarse information at any or all of the dimensions provide little anonymity.”
The process of anonymizing involves stripping out key information from credit card data, such as only providing the neighborhood where a purchase was made instead of the specific location, or only providing data on a 15-day basis instead of a one-day basis. The study points out that even with these kinds of “anonymous” credit card records, an individual can still identified with “just a few additional data points.”
The study also highlighted that “Women are more re-identifiable than men in credit card metadata.”
Of interest, those with higher incomes are also easier to identify, probably because they “have distinctive patterns in how they divide their time between the shops they visit”, according to the study.
The researchers made an urgent call for more advanced technologies besides basic anonymization to protect personal privacy.