“Today, we get an answer of sorts thanks to the work of Amy Zhang at the Massachusetts Institute of Technology in Cambridge and a couple of pals. These guys point out that when it comes to online services such as movie providers, several individuals often share the same account. That means that the choice of movies and the ratings on this account are the combined choices of several different people.
The question they set out to answer is whether it is possible to identify shared accounts simply by studying the ratings associated with it. And if so, how should recommendations be modified in response?…”