"I'm curious how one would describe the "risks" involved in this particular study: "You may find yourself experiencing slight emotional shifts of some tiny percentage point either positively or negatively, with allowance made for the overall pathetic mess or general cheer of your self-selected friends group." I would also point out that Mary is simply wrong when it comes to quite a lot of sociological experimentation. When the observer effect not just possibly but definitely would swamp out any signal, quite a lot of manipulation to get around that fact is the order of the day. I think the overall complaint about the study misses something extremely important: all the participants, and in fact everyone on Facebook, has already consented to allow Facebook themselves to manipulate and manage their news feed in any way they see fit, by any metrics they enjoy, and all participants are free to leave the experiment at any time. FB has adjusted the "Top Stories" weighting mechanism dozens of..." - Alexander Williams