The news that researchers could use Facebook feeds to "predict" whether you suffer from any of 21 medical conditions came across as impressive, but also unnerving. The conditions included some potentially embarrassing ones, such as sexually transmitted diseases, several that might put people at risk of discrimination, such as depression and psychosis, and pregnancy, which some people might feel should be their news to tell.

But don't worry. Big Brother doesn't really know about that infection.

Once you get past the headlines, the actual scientific data showed only that the researchers could guess better than blind chance when given access to people's Facebook feeds — not predict that you had any particular condition. For just 10 of the 21 conditions, the Facebook feeds were more informative than basic demographic data such as sex, ethnicity and age.