The growth of “big data” changes the very essence of modern markets in an important sense. Big data are nothing but the digital traces of a growing number of people’s daily transactions, activities and movements, which are automatically recorded by digital devices and end up in huge amounts in the hands of companies and governments. Payments by debit and credit cards record timing, place, amount, and identity of payer and payee; supermarket loyalty cards report purchases by type, quantity, price, date; frequent traveler programs and public transport cards log users’ locations and movements; and CCTV cameras in retail centers, buses and urban streets capture details from clothing and gestures to facial expressions.
This means that all our market transactions – purchases and sales – are identifiable, and our card providers know a great deal about our economic actions. Our consumption habits (and income and tastes) may seem more opaque to scrutiny but at least to some extent, can be inferred from our locations, movements, and detail of expenses. If I buy some beer, maybe my supermarket cannot tell much about my drinking; but if I never buy any alcohol, it will have strong reasons to conclude that I am unlikely to get drunk. As data crunching techniques progress (admittedly, they are still in their infancy now), my supermarket will get better and better at gauging my habits, practices and preferences.