Big Data Can Figure Out Who's Buying What, Even With Names and Numbers Withheld from Credit Card Information

Well, sort of. The idea is that given three months of shopping history, with no names or numbers attached, Big Data techniques can figure out who you are anyway, or at least can match your records to your name (if given your name on a list).

When I read that, I thought: Assuming Big Data has you offering information under your name, such as your location on FourSquare, or saying things like "I just bought an aquarium" on social media.

And that is in fact what they mean.

But so many people dribble out so much of that sort of information... Pretty much, for most people, if you exist online at all, they know who you are and they know what you're buying or just browsing.

Your shopping habits can expose who you are even when you are just one of a million nameless customers in a database of anonymous credit-card records, according to a new study that shows how so-called metadata can be used to circumvent privacy protections in commercial and government databases.

Researchers at the Massachusetts Institute of Technology, writing Thursday in the journal Science, analyzed anonymous credit-card transactions by 1.1 million people. Using a new analytic formula, they needed only four bits of secondary information--metadata such as location or timing--to identify the unique individual purchasing patterns of 90% of the people involved, even when the data were scrubbed of any names, account numbers or other obvious identifiers.

...

Researchers drew on records of purchases over a period of three months by shoppers at 10,000 stores, provided by an unnamed bank in an undisclosed country. Each transaction was time-stamped with the day of purchase and linked to a shop.

...

After isolating a purchasing pattern, researchers said, an analyst could find the name of the person in question by matching their activity against other publicly available information such as profiles on Linkedin and Facebook , Twitter messages that contain time and location information, and social-media "check-in" apps such as Foursquare.

So, like, Be More Paranoid.

posted by Ace at 12:04 PM

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