Mood data is notoriously tricky to collect from people. In
   Facebook's scientific efforts, the new buttons will greatly
   assist in their research of people in what they like, are
   surprised by, love, are angry about and laugh about. I don't
   mind assisting their research. The buttons are good. I dunno but
   I think FB has been trying to legitimize its advertising-science
   by conducting studies and publishing scientific papers. So, this
   is a part of. Everything they do is part of some ongoing study.
   It's their site, so I suppose why-not. Here's an example of FB's
   efficiency: Just after I posted that comment, THIS ad showed up
   next to it. They're getting closer. [1]opengovt   Notice the
   subtle social engineering: "120,722 people like this". Does that
   means 120,722 liked THIS BOOK? Hardly. It means they liked
   Amazon. But... it implies...

References

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   1. http://icopiedyou.com/wp-content/uploads/2016/02/opengovt.jpg