More on the risks of identification and re-identification in large databases, from The Economist:
Frequent visitors to the Hustler Club, a gentlemen’s entertainment venue in New York, could not have known that they would become part of a debate about anonymity in the era of “big data”. But when, for sport, a data scientist called Anthony Tockar mined a database of taxi-ride details to see what fell out of it, it became clear that, even though the data concerned included no direct identification of the customer, there were some intriguingly clustered drop-off points at private addresses for journeys that began at the club. Stir voter-registration records into the mix to identify who lives at those addresses (which Mr Tockar did not do) and you might end up creating some rather unhappy marriages.
Read more on The Economist.