The Myth of Anonymous Data

The Myth of Anonymous Data

Even anonymous data is frighteningly revealing. #NoMoreSecrets

De Montjoye and colleagues examined three months of credit card transactions for 1.1 million people, all of which had been scrubbed of any PII. Still, 90% of the time he managed to identify individuals in the dataset using the date and location of just four of their transactions.…

“To be clear: Reidentification means that the researchers could identify all the transactions that belong to an individual, but de Montjoye didn’t attempt to say which individual. For example, if he wanted to know my transactions, he’d need to take additional steps to cross reference something he knew about me to his data. If, for example, I posted on Facebook about a trip to a restaurant, that could provide the key to connecting me to an entire portfolio of anonymous transactions. “We didn’t try to put names on it,” de Montjoye says, “but we know basically what you need to do that.”